This seems disingenuous to me because you're making the claim that they're saying teachers NEED to carry guns. Tell me what I'm missing if I am but it doesn't sound like they're going to force people to have guns. They're just going to let people have guns if they want them. Those are two way different things.
I would imagine there are plenty of teachers who would much rather carry a gun than not due to that kind of threat.
Personally, I do not think teachers with guns is an answer though and have serious misgivings about it but for other reasons. Carrying a gun requires an extreme level of discipline and you really can't allow yourself to get into any kind of altercations of any kind or even intervene in any kind of dispute if you're carrying a gun because the gun and the presence of the gun makes that situation a life and death situation when it normally wouldn't be.
I think if a teacher carries a gun in school even if it's concealed carry, they should be barred from engaging in any kind of action whose intervention is physical, even breaking up a fist fight between students. But then that's just less teachers in the school that can handle the day to day events that come up.