America was founded on the principle of "innocent until proven guilty". Timothy Kudo was acting as judge and jury for these men and found them guilty with almost no evidence. There are numerous reasons why someone might be digging next to the road at night.
It's only by chance that he happened to be right. He uses the phrase "good shoot, bad result", but if that is the standard he's using for "good shoot", I wonder how many of his kills were "bad shoot, good result".
And it's ridiculous to isolate the responsibility for this kind of action to the soldiers. This is on everyone who accept this as okay--the voters who vote for warmongering politicians, the politicians who start wars and create decision policies that say a shot like this is okay, the officers who give the orders, and the troops on the ground that follow them.