he doesnt have to know. with the small river bet, he only needs to be right 1/5 tries to break even. while it is very brave to make a bluff the size of what a value bet would be, if he has a big piece, youll never lose him.

and there really wasnt much that beats him. once you bet out small on the flop, you really lose the chance to represent the queen later in any meaningful way. the queen actually gives him more outs as hes open ended, and you lose your three kings. he missed a chance to raise on the turn, imo.