Knocking him out in one hit would have been a sure fire way to have Sebek idolize his strength. Although, Sebek is already impressed at the speed in which he moved in front of him to protect him. That alone tells him that he's picked well. Such quick reaction and desire to shield someone is among what Sebek wants to hone to better his service to Master Malleus.

"The safety of others is paramount!" Sebek says with a nod. He will exit into the hallway and try to direct people away from the gym until everything has settled down.

That's... usually what he's told to do in these sorts of situations, so he does it without thinking.