He's saying that the teacher should have called her parents before the cops.
How? By leaving the room and his kids unattended with a student who is causing a disturbance? The thing that we are told we can never, ever do? Teachers don't have parents' numbers on speed dial; he would have had to have had some way to get her out of the classroom and escort her to the office, which she refused to go along with, and it's not like he could have used any kind of force to do so. I guess he could have escorted all of his students out of the classroom at the same time and left her there, but it's really a no-win scenario for a teacher. When a kid figures out that there are really no consequences for them doing whatever they want, it's hell for a teacher, because they're right. I wish there was another avenue besides police, but these days, there really isn't.