Blanket bans on former Trump officials are excessive. However, it is a perfectly reasonable policy for universities to not give a platform for people who worked to undermine US democracy. https://www.washingtonpost.com/education/2021/01/23/trump-appointees-universities/
Wrote about this the day after the Capitol insurrection, anticipating that universities would communicate to their stakeholders the importance of democracy, while still accommodating people opposed to democracy. https://twitter.com/donmoyn/status/1347190258224553986?s=20
Grennell took active part in Trump's construction of the Big Lie. He held a press conference alleging mass voter fraud in Nevada. The night of the Capitol insurrection he was on Hannity, still pushing the claim of election fraud that drove the mob.