I disagree with you on this. I know it's risky for one to trust the next person when it comes to what has to do with money, but then again, if you don't trust anybody, do you even trust yourself? And if you are a married person, you, as the husband or wife of you, don't trust your spouse enough.
Why get married to them in the first place? To some extent, we need to take the risk of trusting one or two of our family members. Besides, all those wealths that you are indirectly making are supposed to be for the family, so what's the point of totally blacking them out?
It's his choice and he's happy with it so we don't need to argue with them anymore because it won't change anything . Even the love of loved ones can't change their minds , so is the advice of strangers worth listening to?
If he can't even trust the one who gave birth to him , then there's no one else worth his trust . I bet he never wondered why he wouldn't be alive today without his mother .
I also wouldn't be surprised if he gets married later and his kids treat him the same way he treats his mother . This world is very fair, how we treat others , we will receive the same in return.