Obviously, this was bad enough that the teacher, principal, and a school administrator thought it required a police officer to intervene. They can't just show all the students that the rules are optional. What little respect those kids had for their (verbal only) authority would have evaporated. They NEEDED to escalate it.
Likely because teachers cannot touch a student, and when they exhaust their options, this is all they have. I bet there's more to this story than CNN is reporting. We all know how they love their narratives.
What we do know is that she was asked over half a dozen times by FOUR authority figures to get up and go to the office, and she refused.
The cop didn't just run in and pile drive her. He came in and asked her to move, then asked again, then gave the final ultimatum "move or I'll have to make you move".
She's a victim, all right, of he own arrogance, ignorance, and her parent's inability to instill even a little respect for authority in her.