have the right is a reason to hit someone
Why is having a right to hit someone a reason to hit them? I have the right to smash my own hand to pulp with a hammer but the fact that I have that right isn't a reason for me to do it.
Now they should have given him a chance to walk away again but that isn't a requirement. They can keep hitting him till he leaves.
So you're saying the police have the right to hit whoever they like for as long as they like, all they have to do is prevent them from leaving the area? That's crazy.