But violating due process is itself a crime, for which he would be immune. It’s immunity all the way down.
Now what I’m wondering: How far down does this immunity go? Others in the Executive Branch has duties they must carry out, and also have vested interests in not being prosecuted for “official acts” after they leave government service. Since their authority to act ultimately derives from the president who appointed them, should they also not have this immunity?
If I’m, say, the Director of the FBI, can I collect information on anyone I suspect of being a danger to society, and use those files to blackmail them? Can I assign agents to follow anyone I deem to be a threat? Collecting information and assigning agents are all just part of doing my job, after all.