I asked, "Are you saying that because she's wearing heels and lipstick?" "No, no," he answered, flustered.

A "You could be right." preceded by an unflustered pause for thought may have been a better reply. It seems rather likely that he was using those obvious mechanisms by which an individual signals identity to infer things about that person's identity. Different personal presentation would certainly have created different inferences about correlated traits to at least some degree.

Moreover, providing "Because she is a woman" as ammunition to someone who has already signalled their aggression and sexual-politics agenda is just crazy. Poorly played anonymous man.