Amusing hand at a 1/2nl table

[rja87]

I was at a 1/2 100 max NL table when I saw this hand, could not believe how terribly it was played. I've thought about it and cannot possibly find a thought process that could have been going through his head. Can you?

MP makes it $7, gets 2 callers, then the SB (who has about $90 in front of him) reraises to $27, all 3 players call. Flop comes Q76 with 2 clubs. Everyone checks. Turn 8, checks around again. River 10, it goes check, bet $20, call, fold, and then the small blind folds face up...with QQ. He then goes on to defend himself by claiming "I was right. They both had the straight" after they both showed J9.