I think I see where lwestatbus was headed. From the OP, I could see a state issuing a standard CCW permit and some kind of endorsement for campus carry - much like some states do for adding a motorcycle endorsement to a driver's license. It says you've had the extra training/experience to be able to safely operate in a different environment.
Not that I necessarily agree, but I don't see this as a big deal. An adjunct course for an extra $50-$120 that covers specific differences for campus situations (or crowds perhaps). But the problem here is that in the aftermath, a it could give a prosecutor extra leverage to criticize anything you did.
In any target-rich situation - a campus, the mall's food court, a concert, inside a busy McDonalds, etc. - if the shooter is not stopped, anyone remaining in the area is a likely fatality.
I've mentioned this in other threads, using the San Ysidro, CA., McDonalds and Luby's cafeteria as examples. When a madman enters and begins firing indicsriminately, few people will immediately vacate the area. Most will sit in denial for several seconds before trying to leave or get their family to safety. Their movement may get them killed. Hiding under the table might get them killed too. If no one takes defensive action, scratch off anyone remaining inside after the first 15-30 seconds.
If a CCW holder engages and neutralizes the subject, but one of the his/her rounds injures another person, it is still a net gain if people walk out of there alive. Resultant injuries and deaths should be litigated against the estate of the crazy shooter for initiating the situation.
As far as college shootings go, the same thing applies. VTech showed us that doing nothing results in mass casualties. A psychotic with a plan can delay arrival of LEOs with a simple chain and padlock. All those "potential backstops" become, instead, "potential fatalities".
To lwestatbus' scenario posted above:
Lacking any indications of violence from the gun toter in the hallway, it's a no-shoot. Since classroom doors usually open outward I'll be in a kneeling barricade position with the door open a minimum. If I have to look around the door, I'll be ready to reverse inside and defend the door from intrusion - IF it turns out he is the shooter. If he begins gunning down people in the hallway, I'll have to decide if I have a clear enough shot at any given moment or not. If not, other tactics may be employed, up to and including closing the door and defending my "local space" [classroom].
CCW holders don't have to engage directly either. They can be the "rear guard" on the door as other student exit from windows or other egress points.
I'm neither a SF operator nor a highly skilled SWAT member. My goal will be to minimize contact and help others escape and/or remain secure. If opportunity permits engagement to end the conflict, I may take it to end the threat.
BillCA in CA (Unfortunately)