If your read is that he is never folding then it seems pretty straight forward how to play the hand. If you hadnt mentioned you thought he was never folding Im sticking my stack in right there. I mean, most likely utg donk bettor is typically calling behind you on the flop but most likely done with the hand on turns he doesnt improve.
I mean trust your read, just dont mistake someone putting off a strong image because they are scared of having to fold to a big flop 3bet or shove