Live 10/20

So he has the AK flush, as well as aces and nines, and one of the kings, and he is actually considering tossing it to a single bet on the end from the guy with exposed fives. I simply do not believe it. Even without the nines im not tossing this hand. Bet the river, why check? The other player is not a worry, he is far behind you for sure, he has just flat called so he doesnt have a house, he is almost certainly way behind you. Your play just really confuses me.