Not that it ever was. Here's Jesse Walker on the right-wing variety:
The neocon activist David Horowitz even toyed with the idea of "adding the categories of political and religious affiliation to Title IX and other existing legislation," thus making conservatives an officially protected class. He eventually gave up on that notion, but he's still pushing an "Academic Bill of Rights" that would let students lodge official complaints against professors for the topics they choose to explore in the classroom.
There's much more; read the whole piece.
I recall recently reading somewhere about a Republican state legislator complaining about classroom bias and insisting that "both sides" should be represented. It didn't seem to occur to him — why would it? — that there might be more than two sides to any question, or that sensible people might not be eager to take "sides" at all.
Not that right-wing political correctness is anything new. In American Conservatism: An Encylclopedia the entry on "academic freedom" has to begin by noting the irony of conservatives casting themselves as champions of academic freedom. William F. Buckley's God and Man at Yale was precisely a call to silence or dismiss professors teaching un-Christian and socialistic doctrines. And the first mass-membership conservative youth arm, before Young Americans for Freedom, was a group called the Student Committee for the Loyalty Oath.
Of course, Buckley was writing about a private institution, Yale, which ought to be able to hire and fire whomever it pleases, for whatever reason. And it shouldn't be taken for granted that agents of a foreign power — which is what the Communist Party, USA was representing, after all — must be allowed to hold jobs at state universities at taxpayer expense. Even with state universities, however, I'd rather see the university itself make the decisions about hiring and firing on ideological grounds, subject to public pressure perhaps but free from direct state or federal interference. If we're going to have state univerisities at all, as well as research grants and federal student loans and other subsidies to private universities, they should nonetheless remain as insulated from politics as possible.
At least a few old-guard conservatives rejected the litmus tests that many of the Cold Warriors demanded. Russell Kirk and Robert Nisbet both wrote books — Academic Freedom and The Degradation of Academic Dogma respectively — defending a broad interpretation of academic freedom, in Kirk's case in direct opposition to Buckley.