With half pot your giving villain better odds to call, he may not call full pot, when you decide to bet full pot on the river what bluffs do you have in your range ? Sure he’s getting 2:1 but it looks like a value heavy river bet. so he may be more inclined to just fold whereas Half pot he can call with more worse hands, river diamond completes straights and flushes. Assuming villain will call to a river shove with 2 pair seems slightly optimistic. If he comes over top the half pot for an all in its w.e we are getting too great pot odds to fold.
If you shove the river he needs to be good 1 out of 3 times, what hands does he have 33% Equity against that you shove on the river given the lines of play?
In my thoughts it looks pretty rough scenario/decision for villain if hes holding 2 pair
he can definitely have 2 pair like AK,AJ but I think alot of your FD hands you would semi bluff with got there on the on the river, I dont think he should be afraid of the Straight because you having QT would be weird given your line except maybe only QTdd which is 1 combo.
If we are giving villain AJ,AK most of the time then..
He is beating hands like A3,A7, a hand Like KJ with J of diamonds K♠:J♦: ( can't see hero barreling KJ on flop with no backdoor diamond but maybe)
And hes losing to all flushes, 77,33. and possibly losing to AK if he hold AJ. I think if the river wasn't a diamond it would be an easier decision perhaps but I don't think its an easy call for villain given his range on a 2:1 river shove. Thin value 1/2 pot seems fair but to each their own.