I assume he would bet a 7 on turn,maybe 33,77,88-TT would checkback turn and turn his hand into a bluff. What if you had TT-KK? Would you bet/fold this river? I think his expectation is to fold out your middle type hands when he bricks FD, get paid when you actually have a Ace and he has better. Bet-calling is my river line as he only wins here a small % of the time. The rest is air+middle hands turned into bluffs.