Sort of like that, I mean you don't want the survivors from the bottom tuning your car, or maintaining your boat or plane. Dumb but placid and trainable for food production, and intelligent and placid for maintenance and security would be the plan if I was at the top. Hold a sword over your chattels heads via family to ensure they don't poison your food and it is easy living from after the great reset. Now that I think about it more, there is no need for the left side of the bell curve, any survivors will do whatever you tell them for access to potable water, food and medicine.