Not many answers, but some penetrating philosophical questions for Talbott and his account of "justice" in his universalism.
I shall confine myself to his claims about the relation of justice and mercy, which are not only central to the essay but also probably the weakest and least developed part of his larger project of defending the universalist view of salvation.
Normally, one of the essential differences between the two concepts is that justice is based on desert whereas forgiveness is not. Talbott, however, insists that mercy and justice are both deserved, that God is obligated to forgive us.
Retributive justice is a matter of settling for less than the best, of bringing a measure of truth and equality when the deed and some of its consequences cannot be undone. We execute a murderer or imprison a rapist not to restore the victim, but to settle accounts when restoration is not possible. And in this justice of the appropriate sort is done.
Talbott is right, there is something odd about saying that punishment 'cancels' the crime, and retributivists have often been guilty of such talk. However, I think there is something equally odd about the suggestion that future reconciliation and restoration 'cancels' the crime.
In other words, what Talbott needs to develop is a notion of justice. Without it, claims that mercy and justice require the same thing are at best premature. Indeed, without it, one worries that Talbott may not be interested in advancing serious claims about justice at all.