Continuation of my bad Stud/8 thread, question

[Bartholow]

This came up in my hand post, but was so buried that it didn't get any responses.

In the hand, I had split kings and reraised an unknown player who completed first in with a 9 showing. It was asserted that I should have just folded, as anyone "reasonable" with a 9 showing should have (99)9, (AA)9 or (KK)9 to play. So what I'm wondering is how often an unknown player will be this "reasonable", specifically in the Party 10/20 but also in general?

In other words, when someone raises with a 9 up, doesn't Bayesian analysis tell us he's more likely to be a moron than have AA, KK or 99 down?