There were people concealed carrying on the Oregon campus and they didn't do anything to stop the shooting.
Yup, they weren't permitted to do so.
Anyway, I get it, even if they were permitted to do so, it's a risky proposition. The cops could show up and kill everyone with a gun, good or bad. A gun in the right hand two buildings over is no good. But for example, that dude who was holding the door shut, had he had one I think it goes differently. I mean in this case the guy is in a room, and is going one by one asking their religion, and then shooting them. If any one of us were in that room, armed, it would have gone differently.