I read somewhere that the grandfather isn't leaving an inheritance to this heirs.
I don't know if it's true or not. Yet, this type of behavior might be part of the reason. Who knows?
I was struck by a few thoughts when I read this story. First, it's pretty ugly... What he says is clearly not going to win him any support. Though, I've never heard of him or his antics before. So, maybe this was just a stressed out one-off and he shouldn't be totally judged on that. That said, it's not surprising. I've experienced a fair amount of entitled people in my life and it's possible this is just another one.
Just another little mess in Hollywood.