So there's a quote of which I am very fond:

"Secularism is a name Christianity gave itself when it invented religion, when it named its other or others as religions." Gil Anidjar, "Secularism" in Critical Inquiry 33 (2006): 62.

What Anidjar is saying is that when all you have is one prevailing structure, whether it be Christianity or the white, male, privileged normative discourse of the academy prior to the the 1960s-1980s, which then finds its universalizing claims challenged, whether by Hinduism or feminism, that prevailing structure gets defined as "neutral ground" while the challenger is made "political" or "a religion." (Note that Anidjar isn't really talking about the ritual or cultic practices of Christianity, but the cultural existence that comes with it - "secularize" means "that thing that used to be culturally Christian but now isn't")

To put it more simply, the period before the 1980s was not a "politics-free zone," it was a zone where everyone more or less held the same politics. The more recent period is not marked by the introduction of politics, but by the introduction of different politics that challenged the normative discourse. But once there's disagreement, it becomes very easy for the previous, normative discourse to redefine itself as "neutral" or, in this case, "politics-free."

You asked about the sciences, so here's a small example of this phenomenon occurring there. It's widely acknowledged that the so-called "soft sciences" are the fields of the academy into which women have made the most progress in terms of gender parity in job placements. And it's also widely acknowledged that women first started to make inroads into these fields in the late 1960s. Do you want to guess when the terms "hard" and "soft" science - where "hard" science is explicitly more neutral and serious - first appear? Well, the late 1960s, of course.

In short, always remember that the act of calling something "unbiased" or "apolitical" is itself a political claim.

"Literature, largely a politics-free zone until the 1980s, has become hostile territory."

The author here is referring to the rise of identity politics and the "postmodern turn" in the academy. Much of this was driven by scholars in literature departments, who were heavily influenced starting in the 1970s by Continental philosophers and theorists now associated with the discourses of post-colonialism, post-structuralism, and various forms of Marxism. These are some of the famous names you might have heard of: Michel Foucault, Jacques Derrida, Louis Althusser, Homi Bhaba. Many of these scholars were informed in particular by Derrida's concept of "deconstruction." Deconstruction itself is a complex, complicated, and contested notion among philosophers and other academics. However, one way in which it was used in the 1980s was as one of several tools to call into question the validity of the "canon" (meaning the set of works of literature, art, or other cultural objects that is broadly accepted by scholars as worthwhile and enduring). Many scholars pointed out that the canon is (was) totally tilted towards the productions of white straight men, usually dead (the infamous 'dead white males'), and thus left no room for people of color, women, and other minorities to see themselves represented in the body of "respectable" or "classic" literature. This impulse towards questioning the canon joined with a postmodern desire to question the idea of a "metanarrative," or an over-arching, controlling narrative of the development of history and society. Hegel (who influenced Marx, among many others) is perhaps the most famous example of such a metanarrative. Put crudely, Hegel's philosophy of history emphasizes the ongoing development of society in an always more perfect direction, towards a fixed endpoint. For Marx this endpoint was communism. For others it has been liberal democracy/capitalism more-or-less as practiced in the United States.

The various "-isms" as well as canon deconstruction have long been bugbears for many conservatives. Critics of these movements have argued that the canon is not racist in intent, and that these works of literature are truly great, and that questioning them is an act of naked identity politics that betrays the dictates of good scholarship. And this is the crux of your question. There are two related but also somewhat opposite ways to answer this, in my view.

I think it is fair to say that at the most basic level, literature was less nakedly political before the 1980s. Scholars were happy to teach and research Shakespeare and other canonical works, and the deconstructionists and cultural studies theorists of the 1980s brought politics to the forefront in a way that was not the case in earlier eras. However, this also creates a false dichotomy between "non-political" tradition and "radical" change. The people who challenged the canon would say that they were themselves challenging a political choice, namely the choice to privilege only one sort of perspective in the works that academic gatekeepers have decided are valuable. In other words everything is political, and to pretend otherwise is to reaffirm the unequal basis on which much of society was formed.

Much of the rest of the article isn't really about a historical question, so I'll refrain from digging into it too much. I will end by saying, however, that this view of 1980s-style culture-warriors running roughshod over the canon is a bit dated, though it is still very popular among conservative activists. Those were the tactics and concerns of earlier generations, and today's literature scholars have taken the field in their own interesting directions, rather than simply continuing the agenda of their forebears. Though, of course, many people who got their PhDs in the 1980s are still teaching, so it would also be wrong to say that this is a completely dead set of theoretical and political positions in the academy.

Hope that clears it up a bit!