i wouldn't fold before the turn and could definitely find a call on the river. considering the smallish river betsizing he is repping almost exactly Ax, a narrow range considering he doesn't get to the river with all Ax he opens with and cbets on the flop, AND there are plenty of non Ax draws he could have been barreling on the turn that he would turn into a bluff on the river. he only needs to have a missed draw ~35% i think for a call to be profitable.