Justice, not what he wants, is what should matter.
On the one hand you have a painless, humane death. On the other hand you have years and years of sitting in a cell, 23 hours a day, solitary confinement, no touch with the outside world at all. To me that would be sheer hell, and I want Moussaoui to spend the rest of his life in our hell before going on to the other one.