I mean, the logic is technically sound, but not for the justification he’s trying to make lol. Perhaps it’s just culture, but one’s family is right up there too. Your wife marries into your family and you marry into hers. If you or your spouse cannot stand the other’s family to the point you are trying to cut the other away from their family, you need to work through that. Your daughter is your mother’s grandchild. There is a level of respect that she must hold for her grandmother as well.