As a general principle academic tenure protects an academic against being fired for expressing unpopular views, but it still allows the university to fire the academic "for cause". Academics with tenure are not totally immune from losing their positions, especially if they engage in misconduct or failure that does not involve merely an expression of unpopular views.
In the case you are talking about, MSU has referred Dr William Strampel (Dean of Medicine) to Faculty Review Panel who will decide if there is "cause" to remove his tenure. The university alleges that he has failed to satisfy his job requirements in his administrative position, by failing to enforce guidelines on Nassar for the protection of students. There is certainly no suggestion that Dr Strampel was involved in the sexual assaults committed by Nassar; the allegation is that he did not properly adhere to the administrative requirements that would have restricted Nassar's ability to commit misconduct against students. He is accused of breaches of criminal law relating to misconduct in a public office for these alleged failures, and he is also subject to a review of his position by MSU.
This is an interesting case, because of the separate aspects of academic tenure as a protection of academic work, versus the responsibility of senior academics in their administrative capacities. I think there is a reasonable argument for the position that administrative failures ought to lead to removal from administrative positions, without necessarily leading to loss of tenure as an academic (e.g., Strampel might be removed from holding an administrative position, but still be allowed to work as a tenured academic in a research/teaching capacity). It appears that the university is seeking a full firing in this case, and it remains to be seen what the Faculty Panel will decide.
Update: It appears that Dr Strampel was convicted of "misconduct in office" and "willful neglect of duty" relating to his actions in relation to this matter; he recently lost an appeal against conviction (see news reports here and here).