First, let me say that I agree with Iwestabus' position. I do not think that it is elitist. I do believe that some of it has to do with his training and experience (Welcome home. Thank you for your service.). In my 9+ years of college (and I was not stoned during any of it), I was the vet who sat in the corner of the room where I could see the door and was close to the exit (most rooms had two doors). No scenario in mind - just where I felt comfortable.
Even years ago when I do not think the laws were on the books, I did not CCW at school. These days students are told under no uncertain terms that if they carry, they will be expelled and reported to the police.
In a classroom, the person at the front of the class has a measure of responsibility and power. If gunshots are heard, the students will (somewhat naturally) look to them for direction - in many ways like the flight crew of an airplane. But here's the rub - on the airplane, the pilots may be trained to carry and there are (often) Air Marshals who will be carrying. Not so in the classroom.
There are some changes to the "hard wiring" that happens when one is exposed to hostile fire. The military will train their people to take the fight fork of the fight or flight reaction. Most students will not have the training or experience and will need to be led or they will freeze. This is the context of the OP as I understand it. If I were at the head of the class, I would want to be able to get them to safety and address the threat if need be. It would be a bonus if some students had been trained and were CCW. And if they were also vets, that would be even better.