You must remember that he was violating FEDERAL law by not obeying the flight crew. Does not matter if he is a safety risk or not......it is a federal crime. Also, if the crew allowed him to stay on, what signal would it send to any other passenger, on that flight or any other flight? Is it now OK to only obey the law when you want? The flight crew needs to have authority. To me, when he said "Just kill me" it showed that he was a risk,