Hello Djavu, init.sqf :
instructorUID = ["STEAM_UID1","STEAM_UID2","STEAM_UID3"]; // UID OF PLAYER WHO CAN PLAY INSTRUCTOR
initPlayerLocal.sqf :
_UID = getPlayerUID player; // GET UID OF PLAYER
waitUntil{!(isNil "instructorUID")}; // WAIT LOADING OF instructorUID
if( (typeOf player == "CLASS_OF_UNIT_INSTRUCTOR") && !( _UID in instructorUID) ) then { endMission "Loser"; }; // IF TYPE OF PLAYER = instructor class and his UID is not in instructorUID then the player is kick
Sorry for my bad english.