Ex falso quodlibet. Start with any false statement and you can coherently and logically reason anything from it. That doesn’t make these conclusions correct… (the implication would be technically correct, but that’s not the same as the conclusion being correct).
So arguing they’re not stupid because they can logically reason is kind of stupid in itself, because these people still believe wrong facts to be true
“Certain people in France do this too, so this should be universally accepted behaviour. I am really smart”