Ahhh, you're meaning "we have Bayesian evidence that Person B is less likely to be rational than Person A"?

Yeah I should have been more explicit on that, sorry for the miscommunication!

I'd agree, but I still think it's weak evidence if you're only looking at a single situation, and

I'd still feel I therefore know more about Person A (how they handle these situations) than I do about Person B (merely that they are either ignorant or irrational). How someone handles a situation strikes me as a more consistent trait, whereas most people seem to have enough gaps in their knowledge that a single gap is very little evidence for other gaps.

Perhaps for convenience we can add that person A and B are exposed to the same information? It dosen't change the spirit of the thought experiment. I was originally implicitly operating with that as given but since we started discussing it I've noticed I never explicitly mentioned it.

Basically I wanted to compare what kinds of things person A/B would signal in a certain set of circumstances to others.