But that's not actually the point.
Lets get this out of the way. The president of the United States can be tried for the same crimes you or I can be. That includes if he is in office. This is obvious on it's face. What a president has is, like police officers, qualified immunity. There is a higher bar of presumed innocence given to the police given the very nature of the job. Even then, police can, and are, held to account.
Similarly POTUS has wide latitude when exercising his duties. That latitude is not immunity. An obvious example is that if a president decided to break into a person's home and kill them. That is breaking and entry and murder. Whether he is POTUS at the time is irrelevant.
Since this is all very obvious, why are his lawyers going through this? There are two answers I can think of:
1) The usual delay tactics: Lawyers will make motions, etc. in order to buy their client time. This time could result in the charges being dropped or any other number of circumstances that are favorable to their client. If your client is guilty of the crime they are accused of, these tactics buy time before the inevitable trip to jail.
2) They are setting up other officials, Democrat officials in particular. See, if the court rules that government officials are not immune from prosecution of crimes while they are in office or acting in an official capacity, There are a LOT of officials that would be in legal jeopardy. As I mentioned in my last post, all these sanctuary cities are in clear violation of federal law. If they try to argue that they were acting in their official capacities, well precedent would say "too bad". Not that Republicans actually have the balls to put this to the test, but the possibility would be there.
All that aside, what I'm bothered by is the accepting of the terms. The legal team seems to be accepting the framing of the prosecution:
Their argument in that regard has three main planks: First, that Trump’s actions amount to “official acts” in his role as president and are therefore not prosecutable. Second, that any prosecution of Trump would excessively constrain future presidents and invite partisan prosecutions once they left office. And third, that a president cannot be convicted by the criminal courts if he or she has been acquitted by Congress in impeachment proceedings regarding the same conduct.
The actual issue is WHAT Trump is being charged with, not whether he can be charged with anything. Perhaps I don't understand lawyering, but my contention is that the charges themselves are bogus and should never have been brought because they criminalize constitutionally protected behavior by trying to criminalize legal speech of THIS person. Further they criminalize the stated constitutional right to petition the government. This right to petition includes the president. Lastly it attempts to use the heckler's veto in the form of alleged "insurrectionists" threat that Trump should have known about and thus not spoken.
These are ridiculous charges and THAT is what SCOTUS should rule unanimously about should it reach them.
As for the immunity argument, I think those thinking Trump should have such immunity should step back and think of what they are saying. Do you really want a president to not have to consider the law when going about his duties? I sure don't. As far as I'm concerned executive disregard of the law IS a large part of the problem!