As to your specific question, I dunno. I know that false rape accusations are rare - it is MUCH more common - by orders of magnitude - for rapists to get away scot free than for innocent people to be convicted.
The gray areas come into play when both sides were drunk (which is often the case). Those cases don't generally go anywhere, despite the few high-profile exceptions you hear about.
But no private university is beholden to the same standards of evidence that exist in a courtroom. They get to decide what punishments are appropriate, and how to judge guilt.