I'm not convinced this guy deserves the "coward' label. It is a narrative critical to those who go by "good guy with a gun" solution to gun violence.
Peterson gives a solid accounting of the confusion of that day, and claims fear was never a factor. I believe him. You have to understand the situation before you can shut shutdown from fear. The fact that we rely on 100% situational awareness for something that our mind tells us in unlikely to happen is completely unreasonable. Unless you are in the room where it is taking place, there is a fog of uncertainty over a situation like a school shooting. This guy is perhaps a scapegoat based on 20/20 hindsight, and mistaken assumptions.