While I'm quoting Atrios posters, here's a good bit by "nameless":

I spent some time in the nutty groves of academe (an English department), and I cannot imagine anyone there seriously endorsing radical Islam or believing that America is an evil nation.

The prevailing style seems to be icy skepticism towards everything. To have such beliefs about terrorists or the U.S, would actually require them to take a position, which they are very reluctant to do.

I think that this reflexive skepticism (or distrust) of lefty academics exploited and/or confused as anti-Americanism.

I know that there are some kooks in academia, but their numbers are greatly exaggerated. In my experience, most of the "radical" professors hold relatively uncontroversial opinions in their nonprofessional life. As for their professional lives, holding "controversial" views is a way of distinguishing themselves and advancing their careers. I agree that they are more yuppie than commie.

Considering that the big thing within academe is probably postmodernism (whose entire raison d'etre is criticizing modernist assumptions), this characterization seems to make a lot of sense, and it certainly puts that "anti-American" bit in context.