There will be no blanket immunity...
Any Lawyer just has to stand up and say, if a President kills all the Supreme Court Justices (come by a strange accident or force them to resign), then do the same in the Senate (to point of a massive majority), the President can have a super compliant Supreme Court which could rule that he is President for life (i.e. Dictator)...
He then does the same in Congress. He doesn't need kill, simple intimidation like in Russia works best.. Doesn't matter if he looses, just change the result fraudulently and you have immunity.
I don't think these Judges get it... Thomas is hopeless and I am not expecting much, but the others have to opportunity to severe the cancer.