Preflop, I think it's a bad call. Post flop though, I think it's a pretty standard line. You bet 350 into 650, I'm often floating there with 2nd pair to see what you do come turn. If you check behind turn, he fires on any river, and if you fire again, he can safely get away from it. The problem was what the turn was. If it was anything other than Q234, he folds turn. Without knowing your image at the table, I can't be sure of his line, but against an active opponent, it's reasonable to call the turn, knowing that you can donk-jam the river if you hit, and get called down.

Knowing that you are willing to call his donk-shove on the river if he hits, he's given 9 outs (2 Q, 3 3s, 4 4s), giving him a roughly 20.5% chance of hitting. Implied odds show that he has to be getting at least 20% (was 19.9995%) to make it a profitable turn call to get you to call a jam on the river. So, that makes it very borderline.

He also has the fold equity if a heart hits the river, since that draw is much more apparent to you than the straight draw. So, as long as he can get you to fold a lone A to that 3rd heart more often than not, it turns out to be a much profitable hand.

Obviously he is crushed if you happened to have 2pr/set, but with opening ranges being wider in 6max than full ring, 1pr hands are often overvalued.