When the steward runs on I don't think the keeper immediately knew he wasn't another attacker, almost looks ready to take them on too.
I hope all the admonishments in this thread for the kick after the attacker is on the ground are gentle ones at worst. A person has just been attacked, he tries to neutralize a threat. OTT would be going back in for kicks after the steward has pinned him. All onus of civil rationality were already out the window when the attacker got involved.