My first impulse was check behind for pot control and because we're almost certainly behind, but as people have pointed out before me there is a different play worth considering.

With his stats his range is high pocket pairs with maybe AKish and maybe even AQs though that seems far fetched. He'll have known that he'd be out of position for the hand after the flop, which I take to mean that he's even more likely to have high pocket pairs. The flop is semi-dry so he won't have needed to worry too much about pricing out drawing hands (especially with the three-bet - T8 isn't the most likely holding for Hero) and he could have been intending to check-raise a solid holding.

However considering the read of weak player I would rule out AK and AQs (if that was ever an option) and discount AA. Similarly this makes him likely to worry about AK/AQs type hands held by hero and though we are most likely way behind a JJ-KK pocket pair we probably have a profitable bluffing opportunity - the all-in bet.

Villain has $6 behind and the pot is $5.9, so we're looking to bet $6 to win $11.9 at showdown if he calls or $5.9 upfront if he folds. To win at showdown we have between 10% and 11% equity according to PokerStove depending on if we include JJ and AKo. If villain folds more than 50% of the time the bluff is pure +EV. Since we only have a 10% chance of winning the showdown he'll need to fold about 41% of the time for the all-in bet to be profitable.

He'd still almost have to fold too often for this to be too profitable. He doesn't have to go bluff catching, overlooking that we might hold AK or be holding AA too many times before this is a -EV move. But I still like it.