That being said, for what reason should he have fired him??? He was a tenured professor of PE. He did in fact though encourage him to take early retirement which he did.
Why fire him? Oh, maybe for raping a child. Which is the same reason Paterno "encouraged" him to retire. Firing is not out of the question for a senior collage official, after all, Paterno was fired and he didn't rape anyone.
As I said in another post, either the assistant coach's allegation was false or they were true. If they were false, then the assistant should have been fired, but instead they encouraged Sandusky to retire.