>>515403546
Again, from the parking lot in the back, the roof is easily accessible as its. It's not even that tall, maybe about 10 feet to the top and has no guard rails.
A collapsible ladder can easily be snuck in when no one is looking all you would need to do is drive into the parking lot, park right by the roof, unload it outta the passenger seat, extended it, and climb up with the rifle. This could be done in 30 seconds and he's got roof access without opening any doors and triggering an alarm.
This is a university not a presidential assembly, security is more lax and only centered around Kirk, not the entire area.
Also using your logic, guns are banned on school grounds but guess what? That didn't stop anyone.