boat vs. tag on river

[mterry]

Villain appears to be TAG over a little over 20 hands. My image at the table is pretty laggy, possibly overextending too much on later streets. Speaking of which:

Party Poker 5/10 Hold'em (6 max, 6 handed) FTR converter on zerodivide.cx

Preflop: Hero is CO with K[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/spade.gif[/img].
UTG calls, <font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises</font>, Button calls, <font color="#666666">1 fold</font>, BB calls, UTG calls.

Flop: (8.40 SB) A[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, Button calls, BB folds, UTG calls.

Turn: (5.70 BB) K[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, <font color="#CC3333">Hero bets</font>, Button calls, UTG calls.

River: (8.70 BB) 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
UTG checks, <font color="#CC3333">Hero bets</font>, <font color="#CC3333">Button raises</font>, UTG folds, <font color="#CC3333"> Hero?

Final Pot: 16.70 BB

I was expecting the pop or fold on the river, since a TAG is so unlikely to just call down with much here.

How does the fact that I will never fold to a cap in this situation affect my decision?