safe river fold?

Live 4-8 at the Commerce, 7 handed.

SB is LAGish postflop, always betting if checked to on the flop and turn, but never raised a hand preflop (50 or so hands played) and limping or cold calling into every pot.

Button is also very loose preflop, although he will raise and reraise with his premium holdings regardless of position.

Hero is UTG+1 with K [img]/images/graemlins/heart.gif[/img]K [img]/images/graemlins/diamond.gif[/img]

UTG calls, Hero raises, 2 folds, Button calls, SB calls, BB calls.

Flop (10SB): 9[img]/images/graemlins/spade.gif[/img]J [img]/images/graemlins/heart.gif[/img]Q [img]/images/graemlins/club.gif[/img]

SB bets, BB calls, UTG calls, Hero raises, all call.

Turn(10BB): 10 [img]/images/graemlins/spade.gif[/img]

SB bets, BB calls, UTG calls, Hero raises, Button 3-bets, SB calls, BB folds, UTG folds, Hero calls.

River(21BB): 9 [img]/images/graemlins/diamond.gif[/img]
SB checks, Hero checks, Button hesitates and bets, SB check raises, Hero????