One stupid plot artifice

If Sgt. Millen (Lee Marvin) had such a good idea of who really started the fracas, which he later confirmed first hand when he saw the shoot-first mentality of his hunting party, why in hell would he proceed to order, (1) the shooting of Johnson's cabin, and (2) blowing Johnson's cabin to kingdom come with dynamite? It doesn't make a damned bit of sense. Clearly, the film early on established Sgt. Millen as a man of reason and justice, albeit a drunkard. Then he turns into the mad vigilante and effectively causes the death of numerous others in his party. All he had to do was order all those yahoos out of the area, go back to Johnson's cabin unarmed, and explain that the other jerk (shot in the throat) acted out of his own idiocy. Johnson acknowledges the truth and turns himself in. End of movie.