I think you definitely should've raised the flop or turn. Make him define his hand. But since you didn't, the only possible worse hand he might put that bet out with is a flush. Even then it would be a very dangerous bet since three 2s are on the board. AA, KK, QQ, and AQ just seem much more likely from the way he's bet played it. I can't see him betting that much on the river with a hand like 88 or 99 when the Q hit. I probably would've mucked.