Person A sees that Person C, a player who has the Detective role, issue a command in chat to KOS Person B. Person A then can carry out the KOS on Person B and kill him.
I wouldn't call this an acceptable KOS as you're stating yourself you're just carrying out someone elses KOS. Anyways this is an administrator application so there's technically no need to point it out or for it to even be there. I couldn't seem find any faults with the administrator application itself, wish you good luck.
I wrote it because in rule 2.5 it's stated that if they KOS each other, and you have no clue which one could be innocent, you need to wait until the gunfight ends. However this time, it's clear who the innocent is. It's the Detective.