There is also the Bogdanov Affair: http://en.wikipedia.org/wiki/Bogdanov_Affair. Where Sokal was a deliberate hoax, the Bogdanovs seem to be crackpots. However both affairs show serious problems with the peer review systems in their respective fields.
XKCD probably assume that things he don't understand is nonsense - which is a common held belief. Therefore the further he comes from his own area of expertise, the more nonsensical he assumes the jargon is.
