Passive player bets a generally non-scary river...

Opponent is 70/0/0.84 after 45 hands. I had seen him call down with bottom pair before and luck-into trips by the river, calling down vs KK with Ace-crap on an Ace hi board for large amounts, calling on the flop with a lot of shit...calling weak bets with King hi crappy kicker, etc.
He really had not done much betting that I had seen - at least not in larger pots...one time I'd seen him bet before he had a set, but that was early-on.

Do you push the river here as calling doesn't leave anything worthwhile behind...or fold and find a better than 3 pair spot?

Poker Room skin
No Limit Holdem Ring game
Blinds: $0.15/$0.25
7 players
CO $65.75
_TheHorror_ $24.30
Converter

Pre-flop: (7 players) _TheHorror_ is Button with A A
UTG, folds, UTG+1 (poster) checks, MP1 folds, CO calls, _TheHorror_ raises to $1.5, 3 folds, CO calls.

Flop: 8 7 3 ($3.65, 2 players)
CO checks, _TheHorror_ bets $2.5, CO calls.

Turn: 3 ($8.65, 2 players)
CO checks, _TheHorror_ bets $5, CO calls.

River: 7 ($18.65, 2 players)
CO bets $15, _TheHorror_ ???

Aces no g00t.

Ok - that's the way it seemed to me...this player managed to change up his play on me though...I had basically been waiting for a hand to bust him on while I was at this table as he seemed to be the biggest fish.
Almost any other card turns up on the river and I push...but that frickin middle pair had me more concerned than anything else lol.

I typed something in chat and folded, hoping it might prompt him to show.

He flips K8s...so he basically outplayed me here, given that I can fold AA.

Oh and I forgot to mention - I mostly posted this as I was curious as to how many of the FTR crowd would call/push the river here, given the circumstances, as I wasn't 100% sure of my play and the results suck.

But I can easily disregard the results if the play is read-based, etc.