[soah]

Folding here is just scared poker. The pot is too big and your hand is too strong to let it go. People do bizarre things in big pots. AA with a spade would generally either bet the turn, or call your bet fairly quickly. On the other hand, his turn play is very consistent with AsKx or something. Pushing the river here with AK might not be the best play, but most poker players do make bad plays. I'm actually not even sure that pushing would be too terrible... something along the lines of "the pot is too big for me to fold this hand, and he will call a bet with a wider range than he will bet with, so it's better for me to just bet myself." On the other hand, he could also have KK and be thinking "omg, I bet he has the ace of spades! Maybe if I push he'll give me credit for the jack and fold!" On the other hand, he might have a "slowplayed" trip jacks if he had gotten out of line preflop.

There are just way too few ways you're beaten here and there's lots of money in the pot. I'm not going to lose any sleep over paying off a half pot river bet when someone hits a two-outer on me.