I wonder, what did the court expect these men to do? Their duty was to provide security for vehicles carrying U.S. Diplomats that came under fire at a crowded intersection. Their options were to either hold their fire and hope the terrorists didn’t kill them and the Diplomats they were charged with protecting, or they could return fire and gain fire superiority even though there would surely be collateral damage.
As these men and the U.S. Diplomats are still alive, they made the right decision. If we ever get an American back into the Presidency, they will surely be pardoned, but death can never be pardoned, so, IMHO, they made the right decision.
This would have been better served trial by peers. Unless someone has combat experience, they are not qualified to judge.