"I think it's a good attack to hit someone with if you don't want them to see it coming," he responded immediately. "Especially if they're incapable of feeling it coming at them."

In other words he certainly didn't disapprove. Granted, he was normally straight forward and less deceptive than that in a true battle but--sometimes things weren't always so ideal. If people were going to cheat and use it on him, he might as well approve of what works specially if it means saving the world to do it.