California, like most states, has a “slayer” provision in its probate code that says a kid who kills his or her parents gets nothing even if named in the will. I think you’re right that the withdrawal was due to an inability to get paid, which is supported by the fact that a public defender was appointed. Brother and sister are probably not inclined to help with the defense of the guy who killed their parents.
I guess it's good to know that California still has some intelligent laws on the books.