TPTK on a paired board against a monkey

[AMadison]

I am curious as to why you checked the river. If villian calls everything, what about your flop and turn bets being called caused you to check on the 6. While a 6 could have hit a 78, that's about all it could have hit. I don't know why you slow down with TPTK because you are getting called by a calling station. Did you have reason to believe he would check through or that you may be beat aside from the betting?