I mean, the question is sort of absurd and impossible to really speculate upon. The thing is, most classical musicians lived in a Euro-centric bubble. We simply don't know how Mozart would have reacted to music outside of his purview, because the kind of globalized presence of music as we know it today simply didn't exist. (It would be different if we were talking about, say, Debussy or Milhaud, who were certainly interested in non-classical music from outside Europe.) If Mozart were brought to the modern day, I suspect that, as a theater man, he would be more interested in what's going on on Broadway and the latest operas than he would be Hendrix, but again, we just don't really know. I also suspect he would be more than a bit confused about why distortion and loudness were things people not only enjoyed, but constructed whole genres around. That, I suspect, is where Mozart would have the toughest time coming to grips with rock.

I do think, along those lines, that he would have a bit of an easier time understanding Louis Armstrong. Insofar as 1.) As mentioned, I suspect he would be interested in things like Tin Pan Alley, where a lot of Jazz standards come from, and 2.) The idea of varying a melodic line across several presentations would be familiar to him from the genre of the theme and variations. There are some plausible inroads there.

But of course, Mozart lived a mere 250 years ago. As opposed to the legendary Ling Lun, a character documented in Qin dynasty souces ca. 2200 years ago, or the million-year-old hominid woman. How those musicians would have interacted is anyone's guess.