1) We still don't know if Gibbons is guilty. With the lower standard of proof, it has not been determined he is guilty beyond a reasonable doubt - just more likely than not.
2) It's quite possible, even probable, that Hoke simply believed Gibbons wasn't guilty.
3) The investigation that just occured was likely the first conducted by the University.
4) The current policy requires incidents be reviewed even without a complaint by the victim. This wasn't the case under the old policy and may explain why there was such a delay.
5) It's still unclear what the differences were between the interim policy in 2011 and the current policy that took effect in 2013. Some differences may have existed that explain why the investigation and finding wasn't rendered until the current policy took effect.
6) A cover up to delay an investigation or any findings until now would have gone beyond the football program and athletic department, and would have included other functional areas of the university - highly unlikely.