This is an interesting response, and I suppose it is something with which we can work. I do not think you mean to assert the general maxim “a punishment is just if the victim of the punishment chooses it.” Do you mean to assert this? If so, it would be very easy to show that a punishment cannot be just simply because the victim of the punishment chooses it. For instance, if Bernie Madoff chose to, say, have a vacation in the Caymans as his punishment for his financial crimes, it seems like no one would say his vacation would be a just punishment. I do not think you mean that the justice of a punishment is contingent only on it being voluntary right?
I think you mean that the volition of the victim of a punishment has some bearing upon whether or not that punishment is just. However, this doesn’t seem to line up with our intuitions of justice either. Most people approve of the punishment of children, for instance, who are unable to consent to or even understand their punishments. Nonetheless, I think most would say that the punishment of a child is just because it will be restorative, instructive, or possibly act as a deterrent. Clearly, the justice of the punishment has nothing to do with whether the victim approves of or “chooses” the punishment itself.
Now, I don’t want to upset you, but I would like to point out that I believe the assertion that anyone “chooses” hell is both absurd and disingenuous. I do not accuse you of intentional dishonesty, since this deceptive and euphemistic language is common among modern apologists, but I do want to bring this to any reader’s attention. Do criminals “choose” prison? Do smokers “choose” cancer? Do over-eaters choose heart disease? Of course not! You may answer that these undesired results are natural consequences or proceed inevitably from the act, but I’m sure most people would love to “have their cake and eat it too” by smoking without getting cancer or over-eating and never becoming fat. It is nature who imposes the penalty here. The penalty is neither just nor unjust, simply “natural.”
But consider, who imposes the penalty of hell? God! Nature is blind, impersonal, and is bound by unbreakable laws. But, God has the freedom to allow poor sinners to be annihilated does he not? Yes, when we sin we harm ourselves and others, but it is God who imposes the radically horrific eternal punishment. Why is a temporal punishment not enough? Why wouldn’t, say, a million years of agonizing torture be enough for him? Is he never sated? Does his offense endure forever? Why?