I don't see why not. If the teacher wants to have a gun, I say go for it. I'm not saying it should be mandatory for teachers to have guns, but if the teacher wants to go through the training and such in order to have a gun ready in case of emergency then why not? Couldn't make the situation any worse. If people don't want their kids exposed to that kind of thing I'm sure there are plenty of other gun-free schools to choose from.
Now without using insults, I am open to have a nice discussion with anyone who might disagree.