You identified "deep structure" with "content", and "surface structure" with "form". All I'm saying is that this is not exactly what Chomsky has in mind. The "deep structure" that he is talking about is not "content", as you say. The "deep structure" is interpreted by a "semantic component" to give meaning, or "content". As I understand it, the "deep structure" is still in the domain of syntax. Perhaps this is just splitting hairs, though...
Also, about the "structure" of the IQ research --- I do think it a bit misleading to try to fit Chomsky's points about the IQ research into a syntax/semantics or deep/surface dichotomy, without being perfectly clear that such analogies are rhetorical flourishes not intended literally. He was not addressing any such thing ("syntactically it might be fine", as you say), he was merely saying that such research, since it has nil scientific interest (but perhaps still having interest or "content" in the social domain) can only be of interest to racists ("who believe that each individual must be treated not as what he or she is but rather as an example of a certain category" [*Language and Problems of Knowledge*, p. 164], racial, in this example), no matter what the outcome. He is not saying anything like "it has surface structure but lacks deep structure" or "it has form but not content".
Bill