student reprimanded for tackling a knife wielding classmate

Perhaps you are being too hard on Jarlaxle by taking him literally. I don't believe he's the type of person who would leave someone to a tragic fate if he was in a position to do something about it. What I think he is saying is that by allowing the forces that advocate and preach such nonsense to remain in control, WE are becoming responsible for the societal cowardice and moral rot that now plagues most of "civilized" humanity. He is simply emphasizing the frustration we face when trying to fix the problem.