You don't bring a gun to work. What are the actual odds a car jacker is really going to kill you if you comply? You're actually at more risk if you have a weapon on you and reach for it than if you just comply. They don't want your life they want to steal from you because if they wanted your life too they'd have just killed you upfront and looted your corpse.
So yeah I get that the robber was in the wrong but this guy still took a human life when he really didn't have to.