if a woman won't agree to testify, and the police don't already have physical evidence to use, or other witnesses, then there's no case.
hearsay. not saying it didn't happen, but I heard lots of things from people in college and very few of them were true, and of those, many were still gross exaggerations.
so this was '09? sketchy they would boot him from the dorm (there would be a record of that) and RichRod didn't take any actions. guessing he felt desperate enough that he needed Gibbons to go 1 for 5 in FGs the next season, and Hoke never heard about it. Or maybe he did and told Gibbons any more issues and he'd be gone.