Rarely has a judge’s ruling illuminated the irrationality of our state’s criminal justice system like the one from a Cook County judge that set detective Dante Servin free.Servin was on trial last month for involuntary manslaughter in the March 2012 death of Rekia Boyd. She was killed by a stray bullet to the head, one of five shots the detective had aimed at Antonio Cross.Servin alleged he fired because Cross was pointing a firearm at him. He wasn’t.The city has already settled a wrongful-death suit with …