The pros are frequently a false sense of security. You assume a greater disparity between the competence or relevant ability of the pros and the novices than really exists. Relevant ability is key here. Shooting is a novice skill, knowing what to shoot, and when is the hard part. The less ambiguous the situation the easier it is to solve. Active Shooters are not ambiguous, and from the prospective of a potential victim are much more of a marksmanship problem rather than a tactical one.

I would also point out that a “pro” like the average police officer has far less range time than the average avid hobbyist shooter. A hobbyist shooter is totally unconcerned with learning or understanding department use of force policy, traffic law, or the rules of evidence - standard components police academy training. In my state the firearms training block for police officers in the academy is roughly 40 hours. 40 hours is easily surpassed by most people who like to shoot in a few weekends.

I would also point out that based upon the state of world in the last decade that in any in any classroom gathering of students that it is entirely likely that at least one has prior military service and training, and quite possibly extensive combat experience. I would have no problem saying that a USMC vet of Falluja taking advantage of the GI bill is more of a ‘pro’ when it comes to shooting people who are trying to kill them than a cop just out of the academy.

While you can’t train to be a master at everything, having a working knowledge can at least equip you make accurate evaluations.