Militarizing campuses

We live with a massive societal dilemma. Every time gun use is restricted, the non-criminals will feel significantly more threatened than those who wish to do harm. Glenn Reynolds feeds this worry:
Police can't be everywhere, and as incidents from Columbine to Virginia Tech demonstrate, by the time they show up at a mass shooting, it's usually too late. On the other hand, one group of people is, by definition, always on the scene: the victims. Only if they're armed, they may wind up not being victims at all.
There are a couple of reasons, though, why this approach may not have yielded the desired effect in this case.

Firstly, guns can be confusing:
And new information emerged that may help explain a fateful two-hour delay by university officials in warning the campus of a gunman at large. According to search warrants and statements from the police, campus investigators had been busy pursuing what appears to have been a fruitless lead in the first of two shooting episodes Monday.

After two people, Emily Jane Hilscher, a freshman, and Ryan Clark, the resident adviser whose room was nearby in the dormitory, were shot dead, the campus police began searching for Karl D. Thornhill, who was described in Internet memorials as Ms. Hilscher’s boyfriend.

According to a search warrant filed by the police, Ms. Hilscher’s roommate had told the police that Mr. Thornhill, a student at nearby Radford University, had guns at his town house. The roommate told the police that she had recently been at a shooting range with Mr. Thornhill, the affidavit said, leading the police to believe he may have been the gunman.
Presumably the registered concealed-weapons students and faculty would be the first suspects in any future event like this. Moreover, in a worst case scenario like the one we just had, if a shooting is in progress the one lawfully defending others with a registered weapon could become the victim of mistaken identity and be shot at by law enforcement.

There are and always will be students who own and carry guns on campus, even in so called "gun-free" colleges; whether it be for personal protection or gun fetishism, whatever. But since numerous students would remain unarmed, what Reynolds suggests is creating a group of students who are somewhat responsible for the protection of those unarmed students (faculty, etc.). Guns would literally have to be everywhere all the time in order to protect from madness like Cho Seung-Hui's. And those with guns would be expected to use them in the protection of others in numerous circumstances: witnessing a rape, interrupting drunken scuffles at parties, etc. Guns would be in research labs, the gym, the theater, literally everywhere, because you never know when someone that extreme could strike.

In a sense, this would be like creating little militias on campus. Maybe we've come far enough in our collective madness to think that's a good idea.