What's thorny? We know the expiration date. In four years he is no longer protected. So fine him today. If he fails to pay, pile on additional fines. If, after four years, he hasn't paid, toss him in the clink. Seems pretty straightforward.

In order for a court to "pile on additional fines," it has to at that time have jurisdiction over the defendant and the lawful ability to impose criminal sanctions on him at that moment. I don't know much about NY state penal law, but there's a pretty good chance that the way that the law is written it would automatically give the court continuing jurisdiction over a defendant subject to a fine until the fine is paid. And the power to impose additional criminal penalties - including jail time - throughout that period.

That presents all kinds of issues. Can a court impose a sentence on a President-elect that would give the court continuing power to throw him in jail once he takes office? Marchan probably doesn't have the power to sever that ability from himself - if he sentences Trump to any fine, he automatically is giving himself that continuing enforcement jurisdiction until the sentence is fully served.