Agree. In theory so did the cop. But if you are in the area when it starts, well, you have no option. That tends to steel your resolve. The cop had an option, and he chose not to engage.
The cop was there for a paycheck. Any teacher that volunteers for CCW will be there for something much more. And I do agree, if stuff goes down, there will also be the instinct for self-preservation as well, since they are already in the school and not deciding whether to go in.