The professor in question here did not have a tenured position. He had been offered one by the American Indian Studies Program at UIUC, but his offer letter clearly indicated that his position would be subject to confirmation by the Board of Trustees. That's the typical form of one of these offers.
The professor's behavior during the time between the offer and the meeting of the BoT was relevant to the BoT decision. They are not supposed to be a rubber stamp for the academic departments. The BoT felt that confirmation was not in the best interests of the university. As it was the BoT has now voted twice to not confirm the offer to the professor. A copy of the BoT press release is
here.