Would this young man have “planted evidence” if he hadn’t seen someone else runover by second guessing in a war zone ?
It wasn't his job to plant evidence.
Marine Snipers, and I have known one of the best, know who they are targeting and only kill those that are targeted.
when you are trained to kill that way, you are expected to only shoot those that need killing.
No question that it “wasn’t his job.” A review of what has happened to other men in similar circumstances might provide understanding why he did it after “doing his job.”
And that's exactly what he did. Thus the acquittal on the murder charges. It was his fear of his own side that caused him to guild the lily. He had done his job, but then was afraid he'd be punished, very severely, for having done it. But perhaps that was the minimum allowable punishment given the charge. After all, 5 months is a misdemeanor conviction in civilian life, not a felony.
5 months in confinement, loss of pay, and loss of rank, seems a bit stiff for such an action.. but probably not all that stiff. I'd have left it at time served and loss of rank, why punish his family, assuming he has one.