You asked my opinion. I gave it. The issue goes much deeper than whether disruptive kids should be able to stay in class. A well-planned, engaging lesson should stamp out a lot of disruption because the kids should want to be in the room, learning. Beyond that, schools need robust systems to deal with disruption. We use partner classes. It's usually enough. So a kid from one class is taken and put in another class. The disruption rarely continues when the child is away from his/her immediate peers. If the disruption does continue, the child then goes to SLT. Any child removed from a lesson, whether to a partner class or to SLT gets a detention after school the same day.
Do I sound pi? Good job I read Malory Towers as a child, otherwise I'd have no idea what you mean.