Unfortunately, a 29 year old whack job probably doesn’t have much of an estate to go after. Plus he has been off his parent’s insurance policy for three years, so may be no mental health physician to blame.
Who says anyone would sue his estate? His family will sue the airlines. They put him in this situation, they didn’t prevent the misuse of their airplane. The airlines will turn to their insurance to cover that and the replacement cost of the plane as well. A weak spot right in front of everyone has been outed, that’ll mean changes as well.