Continuity and Consistency are two things that kdramas don’t always get.

the schoolboys were many and he was holding back to avoid charges of physical harm to minors.

I come up with lame arguments to play the devil’s advocate & always be on JCW’s side 😀 :
Argument 1: He hardly really hit the guy.. they both barely scratched their lips when brought into the police station..

Argument 2: He just didnt wanna hurt the young students.. Man’s honour and all yo

I think they explained it that they can easily beat the kiddos but they’re minors and they can’t attack first.