That's a horrible way of looking at it, IMO. We're not talking about a punch to the face. We're talking about extreme, agonizing pain.
If I cut off all ten of your fingers and toes, then both hands and feet, then both arms and legs as punishment, would that be OK? Are you suggesting that if one says capital punishment is OK, that should be OK to? After all, its just "injury" we're talking about, right?
Even with animals, who we kill for food, we recongize its horrible to TORTURE them. Some here even think it should be a criminal offense, or say they would personally kill a human to stop them from doing it.
Are we really now going to equivocate when we're talking about suffering to humans?
Actually, this should be even more obvious to you as an annhilationist. You don't even think God will torture anyone for more than a day as punishment for their sins against him. So basically, you're saying there might be a circumstance where its moral to inflict a punishment harsher (or at least lengthier) than what God will inflict in Hell...
I don't know how you define "moral." I've said that I could envision a situation where torture would be the lesser of two evils. I don't consider it to be a good thing. I've said that as a civilized society, we have to have laws against torture. I support those laws. But this is simply a theoretical discussion over whether it's immoral to ever use torture. I guess it just depends on how you define it. I think you could envision a situation where torture would be the lesser of two evils.