Aside from whether or not a president should be above the law, the people or, in the case of classified information, their representatives have a right to look at the allegations and what Trump said. To block that ability, in and of itself is criminal.
David Frum chimes in with a reference to history....
https://www.theatlantic.com/ideas/archi ... SqzpTh37IoThese treasons would emerge into daylight after the overthrow of Charles’s brother and the Stuart dynasty in 1688. For the men of 1787, these events of the century before their own felt as vivid and central as the civil-rights era of the mid-20th century seems to us nearing the middle of the 21st.
So Gouverneur Morris said, according to notes taken by James Madison:
He was now sensible of the necessity of impeachments, if the Executive was to continue for any time in office. Our Executive was not like a Magistrate having a life interest, much less like one having an hereditary interest in his office. He may be bribed by a greater interest to betray his trust; and no one would say that we ought to expose ourselves to the danger of seeing the first Magistrate in foreign pay without being able to guard agst it by displacing him. One would think the King of England well secured agst bribery. He has as it were a fee simple in the whole Kingdom. Yet Charles II was bribed by Louis XIV. The Executive ought therefore to be impeachable for treachery; Corrupting his electors, and incapacity were other causes of impeachment. For the latter he should be punished not as a man, but as an officer, and punished only by degradation from his office. This Magistrate is not the King but the prime-Minister. The people are the King. When we make him amenable to Justice however we should take care to provide some mode that will not make him dependent on the Legislature.
Foreign corruption inducing treason was the core impeachable offense in the eyes of the authors of the Constitution.