WELL, FOR ONE THING, PRESIDENTS HAVE ABSOLUTE IMMUNITY, NOT QUALIFIED IMMUNITY, AS PROVIDED IN Nixon v. Fitzgerald. In both cases, the immunity is only for civil damages, not criminal liability. But there are reasonable arguments that have been made, including by the Justice Department, for presidential immunity to criminal prosecution — and anyway, if everyone else can argue for, and sometimes get, new constitutional decisions from the Supreme Court, why should Trump be barred? He may be wrong (he probably is, but not certainly) but as usual the righteous indignation that meets a Trump claim is mostly because it’s a Trump claim, not because of its validity or lack thereof.
For the record, I oppose both qualified immunity and absolute immunity, both of which are judicial inventions without any basis in the Constitution — the latter being enjoyed by judges and prosecutors as well as the President — but that’s not the point here. And given the degradation of our political and justice systems, you can probably make a better argument today for immunity from criminal prosecution than for civil immunity.