I KNOW, RIGHT?
I don't know why this, in particular, sticks in my craw so much, but it does. It drives me absolutely bonkers. As you say, he doesn't know Regina, except as a murderer. She's not even the same Evil Queen his grandparents defeated and drove away before his mother was born, which I assume he's heard plenty about. If anything, Wish!Henry should be gravitating toward Charming, Snow, and especially Emma. I'm not clear on whether Emma retained Princess Emma's memories or not (and I doubt the writers know, either. It's just Emma, who cares, right?), but if she does, then she's the closest thing to his lost family he has.