In this case young rooster likely considers kid attacked as somebody that he can dominate. Several options can be used for this. Dispatch / rehome rooster, pen him or kid up, or have kid himself put rooster in its place. You doing will not be as effective as kid. Problem is most kids not rowdy enough to defend interest against a rooster because getting flogged does smart a bit and he will likely have to do the putting in place when the rooster is on the attack. Have your son actually handle offending bird to build his confidence up. Expect to get bitten but have son pack bird about. If bird attacks when released, pick it up and hold it some more. Watch your eyes. With next bird avoid the overly personal interactions between birds and people, especially with the hatchery sourced birds.
Can you explain the last couple of sentences about overly personal interactions. We have had only hens so no problems. I am looking to get a rooster to protect my girls but don’t want any issues with attacking rooster