IMHO It's not even about that. It's about the schools brainwashing and conditioning the kids. Now every kid at that school knows behavior like this will cause consequences.
What would happen if every kid in that school did the same thing at the same time? would they suspend them all?
That would be a beautiful protest. All of the kids simultaneously pointing their ‘finger guns’ at the teachers and going ‘pew pew pew.’ And continue doing it every day until the whole thing is dropped. Do it at recess, do it a lunch, walking to and from school, in the classes and halls. Everywhere all the kids making ‘finger guns’ and ‘shooting’ everyone and everything around.