Interesting flop situation with AT

[DavidSRT]

This is a very loose table. The three bettor was 29.7 vpip and fairly passive post flop, no stats no reads on the SB his second hand at the table.

Full Tilt 0.50/1 Hold'em (9 handed) Full Tilt Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Preflop: Hero is MP1 with A[img]/images/graemlins/heart.gif[/img], T[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises</font>, <font color="#666666">2 folds</font>, <font color="#CC3333">CO 3-bets</font>, <font color="#666666">1 fold</font>, SB calls, <font color="#666666">1 fold</font>, Hero calls.

Flop: (10 SB) T[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">SB bets</font>, <font color="#CC3333">Hero raises</font>, CO folds, <font color="#CC3333">SB 3-bets</font>, <font color="#CC3333">Hero caps</font>, SB calls.

Turn: (10.50 BB) 6[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, SB calls.

River: (12.50 BB) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets</font>, SB calls.

Final Pot: 14.50 BB

My main question is how you play the flop. I can't remember being in this type of situation before. Someone donk into two people who have both raised ahead of him. Meanwhile I flopped a monster, in the middle. I considered smooth calling and inducing a raise from the CO. He was fairly passive though post flop.

I chose to raise, he didn't come along anyway, but...

Would you have done it the same way? I was at a loss during this hand.