I thought of Platt and Matix even before I got to Pax's comment. I would think they were more the exception, than the rule for bad guys; however, I may stand corrected.
My question about the opening question is if you draw the line in what you teach, what prevents the next person from teaching what you wouldn't teach? In theory, you can only sequester the knowledge and techniques which you alone possess. That is what you control. If someone else knows – they can use or teach.
A lack of planning on your part does not necessarily constitute an emergency on my part.