I dont know if I agree completely. A tag is likely to raise up ATo here in position if thats what we're afraid of. We also have a flush draw on the turn that has to be live too. I also think he's going to raise T9 or 44 on this flop because everyone is already in the pot.

Then again, I dont know what he's betting on this river other than AT or a complete bluff (missed QJ, J8)