I don't see the relevance of the reference to post modernism, nor do I see any evidence that is a potent force in contemporary American society. I think that post modernism would be better defined as an intellectual movement resisting centralized control (that is, it can only be defined by the absence of a center). I see it as being a largely flimsy effort championed by a few academics in the early 90's to resist being canalized into the more overtly political (and marxist supported) movements of deconstruction and new historicism. I don't think that any fair-minded observer would deny that there is a very influential and militant leftists element that is willing to resort to censorship, marginalization, and indeed elimination of it its political opponents. I would say that a "true" liberal is tolerant of views with which they disagree, and is open to changing their views, but I don't think the majority of people who call themselves liberals meet that standard. As far as the quote about political correctness, it is pure polemic. I don't see any use in quoting it unless one wishes to engage in polemics.
WOW. I read a book years ago--Black like Me. Chronicalled the travails of a white guy made up to be black. I believe there was a movie made wih James Whitmore playing the guy.