This is the most probable reason for such a policy; however there is a big assumption that bikes will be stored in a manner that inhibits emergency egress or that people will try to take their bikes with them in an emergency evac. Why not just address these issues in a policy rather than banning. I work at Duke U. and do not believe that we have any institutional policy that bans bikes from buildings; however you rarely see them inside. I would guess that this is an issue that is resolved between employee and manager (and/or building committee if there is one). I have room to store mine in my office and have never been challenged.

-G