He was a terrible person. He died a hard death. So maybe. A queen can forgive her vanquished foe. It isn't easy, it doesn't count if it's easy, it's the hardest thing. Forgiveness. Which is maybe where love and justice finally meet. Peace, at last. Isn't that what the Kaddish asks for?
Throughout the play characters grapple with questions of love and justice—whether it is just to abandon a loved one, how to care for others, whether to incorporate villains and enemies into the communities they disavow. Belize's call for Louis to join him in forgiving Roy, which appears in Act Five, Scene Three of Perestroika, resolves some of these questions by pointing out a way to unify people while accepting their limitations. Belize acknowledges that Roy was terrible, and so his sins are not excused. But as Belize notes, forgiveness is only valuable because people are flawed—if Roy had been loving and kind there would be no need to forgive him. Forgiveness drives the final events of the play: it is what allows the characters to rebuild their community in the play's epilogue (Prior must forgive Louis in order to love him and remain friends with him), what permits Ethel to return to the afterworld in peace, what enables Harper to put Joe out of her mind and begin her life anew. It mends the calamities of Millennium and allows relationships and societies to be strengthened.