Is it wrong?

Is it wrong that I'm proud of Liam for yelling "Don't!" to a bully, chasing him down, grabbing the scruff of his neck and that smacking the bully in the back of the head?

William and Wendell took the kids to the McDonald's Playland tonight to let the kids run themselves ragged. The kids had a blast. At one point though Liam yelled "Don't" to a little boy, which scared the little boy who then ran off. Liam chased him down, grabbed him by the cuff of the neck, and smacked him in the back of the head. William placed Liam in timeout, but later realized why Liam had done what he had. The kid was being a Playland bully and was running around hitting all the kids on the Playland. In my humble opinion, that little boy got was he deserved, and I'm glad my little boy stood up for himself and the other kids that the boy was smacking.