The Leftist that was asking that question has basically rebuked the people celebrating Charlie's death. He specifically said what he was trying to do was show that the Left was peaceful. Now, he's having a crisis of faith in the Left.

Poor dude was a Useful Idiot that thought transgenders were least likely to commit crimes. He genuinely didn't realize the gunman that shot over his shoulder, and the man that cheered Charlie's death behind him were very real, and he's struggling to come to terms with it.