How Stupid is my friend?

[Homer315]

My friend emailed me this hand, and we disagree vehemently about his turn play. He didn't have a great read but thought that the players were relatively, though not super, tight. Thoughts? (forgot to add, he "accidentally" hit RAISE preflop. Ignore that stupid play for now)

Party Poker 5/10 Hold'em (10 handed)

Preflop: Hero is MP1 with 6[img]/images/graemlins/spade.gif[/img], T[img]/images/graemlins/club.gif[/img].
UTG folds, UTG+1 calls, UTG+2 folds, <font color="CC3333">Hero raises</font>, MP2 folds, MP3 folds, CO calls, Button calls, SB folds, BB folds, UTG+1 calls.

Flop: (9.40 SB) 6[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/club.gif[/img], T[img]/images/graemlins/spade.gif[/img] <font color="blue">(4 players)</font>
UTG+1 checks, <font color="CC3333">Hero bets</font>, CO calls, Button calls, UTG+1 folds.

Turn: (6.20 BB) K[img]/images/graemlins/diamond.gif[/img] <font color="blue">(3 players)</font>
Hero checks, <font color="CC3333">CO bets</font>, Button calls, Hero calls.