I don't think he's arguing that the categories are immediately transparent at all. I think he's arguing that you can explain what they confuse and obscure with simple, ordinary language.
In my view, Marx's expose of where profit comes from via the explanation of the working day is, in fact, probably the best illustration of Chomsky's point you could come up with. Somebody intoxicated on Big Theory would ramble all over the place about the contextuality and structural over-determination of the hegemonic discourse-enshrouded intersection of structure and action at the locus of the productive process. Marx simply showed what happen behind the scenes.
I was trained to think Marx needed Hegel to do what he did. I now think that's untrue. Marx needed Engels, who was the one who showed the power of looking behind the scenes.
Chomsky is right, IMHO. Show me any Complex Social Theory that's necessary, and I'll translate it into English for you, provided it's intelligible at all.