. . . He needs to shut up for the sake of the integrity of American processes.
There is a Grand Jury.
There are clearly legitimate questions about contact with Russians.
If there is evidence of Trump campaign/Russian collaboration on American election processes, it should come out clearly, fully and in a way that will permit us to deal with things going forward.
If there is evidence of Russian blackmail of Trump campaign officials, or financial leverage over Trump or his family and associates that could rise to the level of blackmail or risk to National Security, that should come out also.
ATTEMPTS TO OBSTRUCT OR COVER UP THOSE TYPES OF THINGS simply cannot be justified (regardless of whether "Hillary got elected").  There is a higher and greater good at stake.  Cries to "stop Mueller" are tantamount to any drug dealer, traitor or murderer in America calling for pre-emptive stoppage of law enforcement investigation against them.
Sitting in the Whitehouse CANNOT confer such privilege.