Presidential immunity case created out of thin air.

Wasn't out of thin air. Lower court said there was no Presidential immunity, even for official acts. No nuance or exception. That can't possibly be the law for every possible criminal statue or official act.

What if Congress were to pass a law making it a misdemeanor for any person to conspire with a federal official to delay any Congressional hearing? Presidents strategize with their Cabinet officials all the time in how to respond to Congressional hearings, including - sometimes - trying to work with their allies in Congress to get the hearing delayed. Can Congress criminalize every such discussion between the President and their Cabinet? Almost certainly not. They can limit the power of any other citizen to do things like that, but whatever official acts are necessary for the exercise of the Executive Power (like consulting with a Cabinet official about official business) probably can't be stripped from the President by act of Congress.

The dissent got in high dudgeon over how far the opinion went in insulating every official act from every criminal law, and I think their criticism was right. But neither do I think that the dissent would support that the claim that any criminal law would always restrain the President in any official act - because then the Congress could simply make it a crime to veto one of their bills for "improper purpose." I think even the dissent would have a hard time accepting that the President could be prosecuted for violating that statute.