I don't think Kirito running down to save Pale Rider would have made much of a difference. He was too far away. Death Gun had his gun aimed at the guy. He was being all theatrical, but who knows if that is even necessary. He could shoot Pale Rider the moment he sees Kirito running down, then shoot Kirito or run away afterwards. Kirito himself said in this episode that they should avoid getting hit at all costs. Wantonly raiding the guy while he is holding his weapon is the complete opposite of that.