Well, if we want to game theory this road (We shouldn't, being that tired is an altered mental state but I love wild hypotheticals), Kings absolutely use courts to help maintain their legitimacy. So do dictators. As an example one of the things in Venezuela was packing the high court so they couldn't protest the de-powering of the legislature. I do agree though if we ever get a fully immune president we're screwed. Previous presidents agreed with that and subjected themselves to oversight, and even in one case, a speeding ticket.