Well his vpip/pfr/ are solid, so I wouldn't presume he was bluffing. Chances are he maybe had two pair from the off, such as A2 or three of a kind, and if this was the case I think he played the pot wrong, especially with not betting till the river. Judging from his vpip/pfr/ he's a strong player anyway, so I don't think he'd see the turn unless he had a decent flop, and he probably just made out he had a flush on the river to put you off. It's a tricky situation but would always be a fold for me against someone who plays so tight and aggressive.