There isn't a word in the Constitution that suggests that a prison sentence can be waived because the person has been elected.
That's true. But this is also true:
There isn't a word in the Constitution that suggests that a prison sentence cannot be waived because the person has been elected.
The first quote is one of those things that used to go without saying. There was a tradition of pretty well following normal ways of such things, to the point that it never really seemed necessary to really codify it into law - just like we have not laws stating that a President can't pardon himself.
After all, why would be need such laws? It would seem crazy to suggest that a President could just pardon himself, or that getting elected to be President conferred a sort of a commutation of sentence because the people elected that person to the office and the functions of the office can't be carried out from a Supermax or from Gitmo.
But here we are.
Our reliance upon sanity rather than code is turning out to be a problem.