If you're seriously concerned for your girlfriend's saftey then make a case for more security; not elevator access. If I was on the committe making such decisions I would probably laugh at your attempt to associate equality with able bodied people having access to the same accomodations as those with handicaps.

As an aside, if rapes really had occurred in the stairwell you mentioned it would be all over the media and likely the school would have security all over the place. Rapes are usually commited by someone the victim knows rather than by a "predator."