No, Led Zeppelin tracks like 'Misty Mountain Hop' and 'Battle Of Evermore' were not considered 'nerd music' at the time.

Firstly, Tolkien was not considered the province of the nerds in the late 1960s and early 1970s, when Led Zeppelin came to prominence and then started filling arenas. Instead, Lord Of The Rings had been embraced by the 1960s hippie counterculture, who saw in Lord Of The Rings a desire to escape modern industrial society and live a more authentic life (J.R.R. Tolkien's descriptions of the hobbits and wizards smoking 'pipeweed' was widely taken by the 1960s counterculture to be a reference to the smoking of marijuana, which the counterculture heartily approved of).

The Beatles were seen to be fellow travelers by the 1960s hippie counterculture, and apparently the Beatles read Lord Of The Rings while in India with the Maharishi in 1968. After returning to England, they had a meeting with Stanley Kubrick about making a version of Lord Of The Rings starring the Beatles. This obviously didn't happen; Kubrick as quite an exacting director was likely not keen on the Beatles' acting, and appears to have felt the book was unfilmable. Tolkien ultimately sold the rights to film Lord of the Rings elsewhere, and as far as the Beatles were concerned, they quickly went on to other enthusiasms.

This is nice rock trivia, and all - but the point is that in 1969, when Led Zeppelin recorded 'Ramble On' on their second album II, with its mentions of Gollum and Mordor, they were just echoing hippie counterculture. They certainly weren't the only hippie acts of the era who referenced Tolkien; there was a band called Gandalf that released an album that year, and an early hippie folk version of the glam rock band T. Rex was based around Marc Bolan and another musician who went by the name Steve Peregrine Took (after being sacked from T. Rex, Took started a band called Shagrat, after an orc in LOTR).

A 1973 article by Greg Shaw in Phonograph Record about the genre of 'space rock' discusses the way that Tolkien was received in music fan culture:

Ten years ago, it was J.D. Salinger; later, it was Tolkien; now, those who comprise the pop culture constituency (high school and college kids, and post-intellectuals of all ages) are going apeshit over science fiction and comic books.

Shaw, in other words is arguing that there'd been a recent shift from fantasy tropes in pop culture to science fiction/superhero tropes, and the likes of Pink Floyd, Amon Duul II and Hawkwind - who had more futuristic sounds in their music than the more fantasy-influenced Led Zeppelin - were about to become very successful (Shaw was definitely right about Pink Floyd, writing the article the month that Dark Side Of The Moon came out).

That said, Led Zeppelin lyrics outside of 'Ramble On', 'Misty Mountain Hop' and 'Battle Of Evermore' aren't explicitly Tolkienesque. Tolkien probably wisely avoids having Gollum enthuse about giving 'every inch of my love' to other characters in Lord Of The Rings, and nowhere in The Silmarillion does Morgoth decide to quit Middle Earth and go to Kashmir. In terms of their influences, chief amongst them is American blues music - Led Zeppelin's wholesale appropriation of old blues and then claiming it was their own is well-documented - and many ideas in Robert Plant's lyrics are influenced primarily by such country blues singers (e.g., Memphis Minnie originally did 'When The Levee Breaks', Blind Willie Johnson originally did 'In My Time of Dying', 'Whole Lotta Love' is pretty closely modelled on Muddy Waters' 'You Need Love', etc).

The other big influence on Led Zeppelin is the British folk-rock of the late 1960s, and the catalogue of seemingly ancient folk songs that such bands adapted into a rock context. Singing prominent backing vocals on 'Battle Of Evermore' is Sandy Denny, the lead singer of Fairport Convention (one of the biggest British folk-rock bands of the era). The combination of British folk-rock and Tolkien makes sense; both Tolkien and British folk rock (as discussed in the book Electric Eden: Unearthing Britain's Visionary Music by Rob Young) was strongly influenced by British pastoralism, a philosophy of art which idealises the pre-modern but is intended for modern urban audiences. Lord Of The Rings has Saruman as a sort of figure of the industrial age, transforming Isengard into an industrial city, and Tolkien deliberately contrasts Isengard with Hobbiton, which is meant to be a more authentic pastoralist utopia of sorts. Similarly, the folk and folk-rock of the 1960s in the UK - such as Fairport Convention, with Sandy Denny singing electric versions of venerable folk ballads like 'Tam Lin' and 'Matty Groves' also harked back to a simpler, pre-modern time.

All of this did influence Led Zeppelin - you can hear it most clearly on the quieter acoustic Led Zeppelin songs, especially on Led Zeppelin III, and 'Black Mountain Side' from the first album is heavily inspired by the version of 'Blackwaterside' by Bert Jansch (another big figure in British folk rock, and an excellent acoustic guitarist that Page was clearly impressed by). And as with the British folk-rock of Fairport Convention - but to a much greater extent - there was a certain irony in the way that Led Zeppelin combined this pastoralist pre-modern music with, well, very loud electric guitar riffs.

This irony - or basically, just how loud and overblown Led Zeppelin were - is probably the most common thing that was commented on by Led Zeppelin in reviews of the era; none of the contemporaneous reviews of their first few albums mention the Tolkien thing at all. There was also discussion of Led Zeppelin's pedigree as valued session musicians (Jimmy Page and John Paul Jones in particular being very in demand 1960s British rock session musicians - there is some dispute about whether all the instrumentalists in Led Zeppelin actually play on Donovan's 'Hurdy Gurdy Man', but it's certainly the kind of thing that Jones and Page would have played on).

In a review of the first Led Zeppelin album in Oz in 1969, Felix Dennis says that:

Few rock musicians in the world could hope to parallel the degree of technical assurance and gutsy emotion [that Jimmy Page] displays throughout these nine tracks. Exactly eighty-four seconds after the beginning of ‘Good Times Bad Times’, the first cut, side one, Page does things with an electric guitar that might feebly be described as bewildering. From then on it only gets better....[drummer John] Bonham’s technique is interesting. It’s nice to be able to listen to a drummer whose use of the bass pedal and cymbals is intelligent without being studied and contrived and at the other end of the stick, powerful without deteriorating into frenzied, feverish thrashing. John Paul Jones plays bass and organ for Led Zeppelin. It’s enough to say that of both instruments he is an experienced, resourceful master.

Led Zeppelin were generally seen as a continuation of what bands like Cream and the Jeff Beck Group had been doing, as a negative review of the first album in Rolling Stone makes clear:

In their willingness to waste their considerable talent on unworthy material, the Zeppelin has produced an album which is sadly reminiscent of Truth [by the Jeff Beck Group]. Like the Beck group they are also perfectly willing to make themselves a two – (or, more accurately, one-a-half) man show. It would seem that, if they’re to help fill the void created by the demise of Cream, they will have to find a producer (and editor) and some material worthy of their collective attention.

Geoffrey Cannon in the Guardian also focused on the heavy rock comparisons, musing about their enormous, very quick success that he felt was because they were oh-so-commercial rather than good:

The surface style of the band is “heavy” ; they’re post-Hendrix, post-Cream, post-Rolling Stones, and know how to refer to such bands, all of which earned a reputation for attentive music which explores new states of mind. Page is just sufficiently reminiscent of Clapton, and Plant of Jagger, to make the band tempting; the more so, because it has no depth and so requires no concentration.

Reviewing Led Zeppelin IV, Lenny Kaye in Rolling Stone said that:

It might seem a bit incongruous to say that Led Zeppelin — a band never particularly known for its tendency to understate matters — has produced an album which is remarkable for its low-keyed and tasteful subtlety, but that’s just the case here.

While Kaye is saying that IV is pretty good, he is adding to the chorus of other rock critics: Led Zeppelin are so successful because they make big dumb rock that’s not subtle but is brutally effective.

The only reference to their lyrics I can find in these reviews is from a review of Houses Of The Holy by Roy Carr in the NME:

Aside from some of the more obscure lyrical sojourns into the realms of magic and mysticism, Zep again take on a number of enjoyable disguises on many of the eight cuts.