I wouldn't iso and I wouldn't c-bet. He has a pretty narrow gap between vpip and pfr... It would be interesting to know at least one hands that he has open limped that he has shown down... or even if you saw him open small pp's, then I think it's pretty likely that he's doing this with strong hands sometimes to fuck with people who ISO WITH ATC.

*caugh*

As played... against an aggro opponent, I don't want to get into a war here, I'd just check back on a paired flop.
I think on the river he has QQ, 33, 44, AA, AQ and pretty much nothing else.
Do you really need someone to tell you that a 5x pot shove on the river is more likely to be a misclick than a bluff.