This is plausibly Chomsky, although the source is a bit peculiar; comments are open for correction or confirmation. It certainly sounds like him, and the remarks about Derrida are exactly right. An excerpt:
There are lots of things I don't understand -- say, the latest debates over whether neutrinos have mass or the way that Fermat's last theorem was (apparently) proven recently. But from 50 years in this game, I have learned two things: (1) I can ask friends who work in these areas to explain it to me at a level that I can understand, and they can do so, without particular difficulty; (2) if I'm interested, I can proceed to learn more so that I will come to understand it. Now Derrida, Lacan, Lyotard, Kristeva, etc. --- even Foucault, whom I knew and liked, and who was somewhat different from the rest --- write things that I also don't understand, but (1) and (2) don't hold: no one who says they do understand can explain it to me and I haven't a clue as to how to proceed to overcome my failures. That leaves one of two possibilities: (a) some new advance in intellectual life has been made, perhaps some sudden genetic mutation, which has created a form of "theory" that is beyond quantum theory, topology, etc., in depth and profundity; or (b) ... I won't spell it out....
Take, say, Derrida. Let me begin by saying that I dislike making the kind of comments that follow without providing evidence, but I doubt that participants want a close analysis of de Saussure, say, in this forum, and I know that I'm not going to undertake it. I wouldn't say this if I hadn't been explicitly asked for my opinion --- and if asked to back it up, I'm going to respond that I don't think it merits the time to do so.
So take Derrida, one of the grand old men. I thought I ought to at least be able to understand his Grammatology, so tried to read it. I could make out some of it, for example, the critical analysis of classical texts that I knew very well and had written about years before. I found the scholarship appalling, based on pathetic misreading; and the argument, such as it was, failed to come close to the kinds of standards I've been familiar with since virtually childhood. Well, maybe I missed something: could be, but suspicions remain, as noted. Again, sorry to make unsupported comments, but I was asked, and therefore am answering.
Some of the people in these cults (which is what they look like to me) I've met: Foucault (we even have a several-hour discussion, which is in print, and spent quite a few hours in very pleasant conversation, on real issues, and using language that was perfectly comprehensible --- he speaking French, me English); Lacan (who I met several times and considered an amusing and perfectly self-conscious charlatan, though his earlier work, pre-cult, was sensible and I've discussed it in print); Kristeva (who I met only briefly during the period when she was a fervent Maoist); and others. Many of them I haven't met, because I am very remote from from these circles, by choice, preferring quite different and far broader ones --- the kinds where I give talks, have interviews, take part in activities, write dozens of long letters every week, etc. I've dipped into what they write out of curiosity, but not very far, for reasons already mentioned: what I find is extremely pretentious, but on examination, a lot of it is simply illiterate, based on extraordinary misreading of texts that I know well (sometimes, that I have written), argument that is appalling in its casual lack of elementary self-criticism, lots of statements that are trivial (though dressed up in complicated verbiage) or false; and a good deal of plain gibberish. When I proceed as I do in other areas where I do not understand, I run into the problems mentioned in connection with (1) and (2) above.
(Thanks to Ruchira Paul for the pointer.)
