Well, maybe this. If the physical punishment of a human being lies on a continuum (ranging from restraint in handcuffs on one end to the most grisly torture at the other end), then if some level of punishment can be justified by a social goal, it seems possible to show that a more important social goal would justify at least a slightly harsher level of punishment. I think that as long as there is no cap on the social utility that could be gained from a punishment, one could theoretically find a scenario which justifies any level of physical punishment. As I pointed out in the previous discussion, and as anglolawyer pointed out here, our society uses physical punishment routinely to affect human behavior. In fact, all of our laws, ultimately, are backed by the threat of physical punishment.
So, if restraint in handcuffs is justified in some circumstances, perhaps tugging on them to cause a little bit of pain compliance is justified in more extreme circumstances. Or tasering. Or putting someone in an armbar. Or punching them in the face. And on and on. I think a civilized society would not inflict pain gratuitously, but rather only to enforce compliance. Does such compliance include divulging information which could potentially save innocent lives? Maybe.