Hand converted with online PokerStrategy.com hand converter:
$1/$2 Fixed-Limit Hold'em (5 handed)
Preflop: Hero is CO with T:d, J:h.
MP3 folds, Hero raises, BU 3-Bets, SB calls, BB folds, Hero calls.
Flop: (10.00 SB) 2:c, A:h, T:s (3 players)
SB checks, Hero checks, BU bets, SB calls, Hero calls.
Turn: (6.50 BB) T:c (3 players)
SB checks, Hero checks, BU checks.
River: (6.50 BB) Q:c (3 players)
SB bets, Hero calls, BU calls.
Final Pot: 9.50 BB.
I would donkbet this turn. You have to protect your hand against two players. If BU doesn't have have an A, he wont bet this turn again and he will just check behind like he did. If he has hand like KK, QQ, JJ, KQ, he will (probably) call this donkbet.
Even though SB bets river I don't think he has a flush. He probably has something like small A.
IMHO... 
Assuming this guy is pretty bad he'll do bad things like check this behind with an Ace thinking he's making a hero play (well he kinda is).
If you held something like T9 and the turn was a 9 I would definitely attempt a c/r but the board pairing is "scary" to bad players so a donk here is better.
If the turn was a J and he bet again I would probably not c/r because the only hands we beat are QJ (if he bets again) and A8-9.
