Presidential immunity can/does only apply to Federal action. It has nothing to do with state actions such as brought in NY for violation of state not federal laws. By convention the clock stops on state and civil actions until the President is no longer in office.
I don’t make rules, I offer personal opinion, such as prosecuting a violent crime such as murder by the President. During term of office the House can indict for high crimes and misdemeanors and the Senate conducts the trial.
In Trump’s situation, he is fabricating the premise that Presidential immunity runs with his natural life instead of ending with term in office.
BTW, the classified documents were removed from the White House while in office, it does not matter when they were discovered. Since impeachment can’t occur for someone not in office, only a federal prosecution can occur. Should he go to jail? no, fines and repay costs of retrieval and return of documents? yes…why should taxpayers bear the expense of his misdeeds?
Regarding your comments about Albany and legislative pay:
state legislators are supposed to be part-time citizen legislators and not depend on the pay for their entire livelihood. Here in CT the legislature passes a two year budget in the full session. In the short session year no new bills can be introduced from the floor, only committee chairs move necessary legislation to deal with societal change or emergency. Our legislators get 40k per year for this part time work