I'm not sure what you mean by rationality making you a more attractive mate. Bringing like-minded people together in a close-knit community will make them more likely to get together even if what the group has in common is halitosis: it doesn't mean halitosis makes you a more attractive mate.

Perhaps the increase in confidence makes members more attractive, but that doesn't mean rationality beats irrationality, just that a confident self-assured rationalist beats a shy uncertain one, which is hardly breaking news. Or am I missing something?

I also think that if anyone feels like they can't stand to be around non-rationalists then they've handicapped themselves to an excessive degree. And also made the cult accusation more justified. If you mean can't stand to be 'with' a non-rationalist, that's more common, though still quite a strong, quasi-religious separation from the rest of the world.