Those aren't things that would otherwise be crimes. He doesn't have immunity from procedure, he has immunity for crimes. He kill the justices, or kidnap them and lock them up in some undisclosed location. He has immunity in those cases. But expanding the court would require passing a law. Passing a law is not an action that the President takes, regardless of any presidential immunity. As for felons not being able to become presidents, any law congress passed to say that would be unconstitutional, because the constitution lays out the only requirements to become a US president. The constitution also limits the ways in which the constitution could be changed, and none of that is within the powers of a president. He could kill Trump, but he can't change the rules about who's allowed to be president.
He still believes that the system works. He thinks the checks and balances work. He believes that, regardless of the recent Supreme Court ruling, that he's not immune, so he won't commit crimes like that. The result might be that the final president of the Republic thought it was more important to follow tradition and live the values that he thought the president should hold, than to do what was necessary to prevent the Republic from becoming a dictatorship.
What's stopping him is "civility politics," even when he's been handed a path to thoroughly purge corruption and fascism from the supreme court, he won't.
The GOP has shown they do not care at all about civility, and will abuse this rule.
To not play by the same rules when people's lives are at stake is a deep moral failure, and shows that politics are simply a game for them.
I wish Dems had that dog in them to fight, even if this was possible. The fact they still go around calling modern day GOP their friends and colleagues says more than enough.
