PokerStars No-Limit Hold'em Tourney, Big Blind is t100 (6 handed)

saw flop|saw showdown

UTG (t4010)
MP (t2135)
CO (t895)
Button (t1715)
SB (t1550)
Hero (t4480)

Preflop: Hero is BB with , .
UTG raises to t200, 4 folds, Hero calls t100.

Flop: (t450) , , (2 players)
Hero checks, UTG bets t300, Hero calls t300.

Turn: (t1050) (2 players)
Hero checks, UTG checks.

River: (t1050) (2 players)
Hero bets t500, UTG calls t500.

Final Pot: t2050

Results in white below:
Hero has 8s 9s (straight flush, queen high).
UTG has Ad Qd (one pair, queens).
Outcome: Hero wins t2050.

what he was thinking with his hand, i have no idea

He's definitely an idiot for not betting the turn, when a flush draw hit, and even more for calling your river bet w/ TPTK...