A group of students has made various demands, ranging from moderate steps (more public access to university police records) to some that go further ($15/hour wage for university employees, disinvestment from fossil fuels). Kissinger allowed student protesters into the admin building, and now faces disciplinary action.
I would include excerpts, but the formatting doesn't seem to work when copy-pasting from the NY Times.
Kissinger's justification seems to be that an administration should be more open to its students. It's hard to disagree with that contention, and the university seems to have taken a hard line by threatening arrests and expulsion to clear the building. On the other hand, that openness needs to be balanced against the need for administrators to work without student protesters interrupting them on a whim. Expulsion seems unlikely in this case except as a verbal club, used by the administration to intimidate and by students to invoke righteous indignation.
The distinction could hinge on whether the university is punishing Mr. Kissinger for allowing students into the admin building, and not for the views he expressed.