It is rarely used. You probably have to order the retiree back to active duty and pay them so you can punish them. These guys may not have a current uniform and may not meet grooming/fitness requirements. The whole thing would be pretty awkward. In not sure offhand who the approving authority is, but it might have to be approved by the Service Secretary. As you can imagine, it is rarely in the best interests of the military service to go that route.