flush vs. pot'l boat

[JJack]

After flop donk with so many players i dont think he has got FD so what can he have at river to bet vs 2 other players?
After all check at turn he know that u dont have Q or 5 so he can think that his small/medium PP is good. He can also have A hight but i dont think that more then 10% time cus he bet river vs 2 opponents. (when there are only UH river that i can understand his thinking that his A hish is good when u check turn)
I would fold river.