People will simply set their messages to /4, /5 etc.
In seriousness, all you do is make the /setmsg engagers use very basic short lines. "Enemies in sight. Firing", instead of "words words words charging the blue guns words le engagabung!"
Using them in Group chat is always handy for targets when it would otherwise detract from your fighting ability, but I would guess this suggestion is for the local/system ones to be removed.
