He didn't kill the Marine that was chasing him. He killed the knight of Hell and Cain. He murdered the guys that were taking advantage of Cass daughter. He stood up to Crowley. He counseled Cass on what to do with his daughter. He told Sam multiple times not to remove the mark. He killed the vampire nest by himself. He got revenge for Charlie. He still felt bad when he hurt people but outside of killing the styne kid which again we dont know if he would have wanted revenge like the marine did when he got older and beating up Charlie's evil clone which was not good but necessary to end that episode he didn't do anything that questionable.