Sorry but that's just who Batman is and has always been for the most part. It's practically pathological with him and is so against his character that to kill a criminal regardless of their crime or crimes would be unthinkable. This has been played out in numerous plot lines across numerous media styles. Even though the ramifications of his 'will not kill' have led to those around him that are allies or loved ones suffering or even dying as a result. One of the best examples of this is the animated movie Under The Red Hood,which really lays bare the dilemma that Batman faces even when it involves someone as close to him as Robin. The Arkham Knight repeatedly brings this very subject to the story whether through the Sub-conscience,internal dialogue with the Joker,who often calls Bats out on the fact that some of these people would still be alive or in Oracle/Barbara case not crippled had Batman killed him years ago. Riddler as well as Scarecrow both bait Batman with his choices as well. This is what makes the character so good though. The fact that he has the skills and abilities and resources to rid the world of the maniacs by simply ending their lives yet will not,no matter the cost. This is what makes him both a heroic and tragic figure unique unto himself. Batman like St.Michael must remain the example of reason over madness,logic over insanity and that right makes might not might makes right.