???
It wasn't that. He didn't know the meaning of a common word, he used it anyway, he failed to pick up numerous hints, he refused to look it up, and he acted aggressively when challenged. All in all, a really bad performance. Totally indefensible on any grounds. Never acknowledged any "brainfart" either. Also, I don't think either of your guesses fit. I actually still don't know what the heck he was arguing about, but I don't think you can read the exchange and fail to see why people think he's subnormal.
I don't think that he's likely to win, and I think you tagged him so he'd come in and derail the thread, which was not going well for you. Kind of a "release the gimp" situation.