Here's my take on it. The one who has to enforce the rules gets to make the rules. I didn't approve of every single thing about how my ex and his wife raised our kids. Stepmom was into bribery--paying them to pick up their clothes, etc. But you know what? It was THEIR house, and THEY got to establish the routine there. I'd occasionally voice an opinion (in a nice and respectful way), but ultimately it was their call because it was their house. My kids knew that *I* wasn't going to pay them for picking up their stuff. I nicely told them that when they were at my house, MY rules applied.
If I were you, B, I'd just make neutral, non-committal noises when he talks and do what you think is appropriate.