I smell some misunderstanding here. I have said that I disagree with the principle that the victims could partly decide the severity of the punishment, because the vengeful are better protected. When you had reacted

It's also optimal for people who profess to be non-vengeful, since the government's vengeance is now fully deniable.

by "it" you had meant what? This system, where the victims are directly responsible for a part of the punishment, or the opposite, where only the government decides?