The Axios article links the SpaceX letter to Elon "slowing down" on Twitter - but the event that correlates to the hard stop is Elon's oldest child publicly transitioning gender and changing their last name.
I cannot imagine what one of your children disowning you does to the self, nor if any amount of wealth paves over the pain. It is the ultimate rejection. I hope he takes it as the call it is to re-evaluate his values, priorities, and actions and improve as a human, if only for the sake of the relationship with his kids.