I'd like to think about it in a more controlling way than that. I prefer that mental orders to a mage are manifested as overwhelming urges to do whatever the order is. That way, the mage is practically guaranteed to do whatever s/he is ordered to do and it leaves the Mordecai's mind less open to a [strike:2to7xx83]plot device[/strike:2to7xx83] clever mage that can figure out how to 'back hack' it, so to speak. It would also explain how Mordecai can get mages to go into battle to defend their slavers (besides good, old fashion brainwashing, of course).
That'd just be my preference. x3
