You just described the negligent operation of a vehicle, which is illegal in many states. The analogy already breaks down.

Let's stick with the facts here. Dershowitz has said that the evidence so far only shows legal activity. People can agree or disagree about that. Frankly, I hope Mueller has secret evidence of illegal activity and that's why he's continuing the investigation.

But you implied above that you don't just care whether it's legal. You also want the investigation to continue if it's legal but not "something the President of the United States should be doing". That is a huge overstep in my view, akin to many reckless police investigations into legal activities. Disliking the President's actions shouldn't be enough to continue an investigation into his affairs.