[nath]

This is a bizarre betting sequence. UTG limps then goes all in for at least 10x the pot?
My initial instinct is that he has AA, probably with the Ad, and is trying to be all tricky and clever, enamored with his own play. "I limped aces preflop and got someone to bet! Now I have a flush draw! All in!"

I realize that doesn't help you put him on a range, but it's such a donk way to bet the hand that I assume he's a donk and would play like this.

I'd muck because I'm not finding a hand he has that makes this better than a marginal gamble, and it could be quite a bit worse.