NL100 Hand: Fold bottom set here?

[SLEEPER]

The first thing mentioned in the post is how our villian is extremely passive.... given his preflop raise, turn checkraise, and then big bet on the river, I would start to get worried that he has a set... a passive player does not turn checkraise and bet out big on the river with AK... the only holding that he could have that we beat, is AA, but I would have thought that he would bet it on the flop.... he is loose, but extremely passive, and yet in this hand, he is going crazy with the betting. This is exactly the type of player that you can safely fold a set too....