Flopped set on a suited flop: Cap of fold?

[Gatts]

PokerStars 0.02/0.04 Hold'em (9 handed) converter

Preflop: Hero is CO with 9[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/spade.gif[/img]. UTG+1 posts a blind of $0.03.
UTG calls, UTG+1 (poster) checks, MP1 calls, MP2 folds, MP3 folds, <font color="CC3333">Hero raises</font>, Button calls, SB calls, BB calls, UTG calls, UTG+1 calls, MP1 calls.

Flop: (14.50 SB) K[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/club.gif[/img] <font color="blue">(7 players)</font>
<font color="CC3333">SB bets</font>, BB calls, UTG calls, UTG+1 folds, MP1 calls, <font color="CC3333">Hero raises</font>, Button folds, SB calls, BB calls, UTG calls, MP1 calls.

Turn: (12.25 BB) K[img]/images/graemlins/diamond.gif[/img] <font color="blue">(5 players)</font>
SB checks, BB checks, UTG checks, <font color="CC3333">MP1 bets</font>, <font color="CC3333">Hero raises</font>, SB calls, BB folds, UTG folds, MP1 calls.

River: (18.25 BB) T[img]/images/graemlins/diamond.gif[/img] <font color="blue">(3 players)</font>
SB checks, MP1 checks, <font color="CC3333">Hero bets</font>, SB calls, MP1 calls $0.02 (All-In).

Final Pot: 20.75 BB