Irony is with reference to sin/sinner, there's also the command to not kill anyone. Imo.
Because of MS's actions, his family has to live with the consequences forever (husband/dad no longer home, a wage earner is gone, family assets will probably be used for his defense, he won't likely be free to be a part of future family milestones like weddings or grandchildren or even funerals of loved ones, missing being a part of daily life, etc.). Whatever the reason, MS chose to be a judge and jury not only to his victim but also for his family. (And everyone else who is affected by these events.) That takes a lot of hubris. Imo and MOO.