You’d have to catch them first. If you watch the video there almost zero hand to hand combat. Their arrows don’t seem to have stabilizers either.
Obviously if this was filmed on video someone could have given one side a machine gun. Would’ve they used it or would have they still opted to maintain the tradition and fight the old way. The battle may have other reasons besides 100% dominating or wiping out the opponent.
Sadly, guns have entered these conflicts since that film was recorded, and there have been far more fatalities. They've changed the dynamic and not for the better. Central government doesn't seem to have much control over big portions of PNG. Language and remoteness are two major barriers to that.