It would also be very easy for a court to decide that executing a political rival is not an official act and deny the President immunity.
What do you think the odds are for this Supreme Court to declare e.g. that shredding official documents (or moving them to the president's private property) is an official act?
Only the President can decide what happens to his records and documents. This has been made clear under Navy v. Egan. Congress can pass no laws regarding classification or record keeping. The Presidential Records Act has a caveat where the "personal records" of the President belong exclusively to him, and it's the President who decides what is personal or not.
That's a fascinating interpretation of PRA, which establishes public ownership of all Presidential records. Specifying if a record is private is the responsibility of his/her staff and done at the time of filing. Of course, Trump has tried to quote from the PRA, but he's not charged with any PRA violations, but under the Espionage Act.
What do you think the odds are for this Supreme Court to declare e.g. that shredding official documents (or moving them to the president's private property) is an official act?