I don't think there's a good answer because any answer to your question hinges on a political decision. From a practical point of view, "holding him accountable" requires a group of politically-minded people to agree that he has committed a crime for which he needs to be held accountable.

Let's say, for the sake of the argument, that there is indeed a law that he has broken. If the people with the power to punish him for it decide not to do it, then whether he actually committed a crime or not is a moot point. We will only know whether he will be held accountable once he is being held accountable.