The 4 deputies were paid and trained for armed intervention. They were paid to put themselves in a potentially dangerous situation, which they didn't do. Looks like that police department has problems with their organisation.
The middle aged teacher is equipped for self defense. He/she is already in the middle of that situation.
Proper training prevents panic situations. When the fear factor sets in (nobody wants to die), one's IQ goes down by 50%, depending on the individual. In those situations, people revert to their training. So if you got no training, you won't know what to do and either freeze or possibly act counter productively. When you're trained, your trained reflexes kick in. A good example are emergency procedures that are practiced by airline pilots in simulators; too late to think about it when an engine quits on take-off if you've only read about it before. It takes a few hours of training for the average person. They are proposing to train these volunteers, and not just give the guns away.
A proper concealed carry course instructs you to keep your handgun kept inside your hidden hoster until you are ready to actually use it. So if you're running towards where the action is, you keep it hidden until you get there and assess the situation first. That way, other armed people will not shoot at you, thinking that you're an aggressor. In any case, it would be expected that the teachers and other school employees know each other
That comment smacks of racism. We've gotten from an 18 year old wearing military fatigues running around shooting a rifle at anybody, to a middle aged teacher who everybody knows in a suit who hasn't revealed his gun yet. In any case, concealed carry courses teach you that you are taking a risk of being mistaken for a bad guy if you draw your gun; but that may be the risk you take for defending yourself and/or doing your civic duty. And when the cops get there, you probably will get arrested and have a bunch of laser sights on you, until they sort everything out. But that's why you volunteer