Teens question authority. It is what they do, its practically hardwired into the DNA. Putting an authority figure in their way for no good reason is just asking for trouble. If that authority figure is a coach or a teacher or a vice principal, even one with a chip on their shoulder, they are at least used to dealing with kids. A police officer may not be as experienced in dealing with kids. And one that decides to arrest a teenager for making "bacon" jokes or being a smart ass, is not someone who should be working in a school.
Who is the cop supposed to be protecting the students from? And who is protecting the students from the cops?