It also bothered me that he made that decision. The Lone Survivor made the decision to allow their enemies to walk own that mountain. Luttrell sealed the destiny of those 19 people who died. May sound harsh; but that is reality.
If you are basing that OPINION based on the movie, Marcus said himself that the movie people to some liberties with that sequence. But he let it slide. I would wager he let it slide so not to sully the memory or honor of his brothers who are no longer with us. Remember, Murphy was an officer, Marcus was a Petty Officer (enisted). Marcus did not make the decision, Murphy did, as he should considering all of the pros and cons of his TEAM members.
But I think his MSM assessment was dead-on though.