There is plenty of distance between the kid and the convoy for someone to yell at him to stop or send him a clear message to. The kid is just being stupid running towards them. I am going to go with he doesn't shoot the kid, and it shows how much restraint he has as a sniper to make good calls.
The only time you gave non lethal shots in Iraq was for vehicles that wouldn't listen to you. You had every right to go from Shouting(verbal/horn,penflare warning) to shooting a round to the ground toward the driver side of the car to putting rounds into the driver windshield if you felt the driver was going to use deadly force. For personal you think are going to cause deadly harm, there is no warning or shooting a person in a leg you shoot to kill. They train you this way for a reason. Too many people were still killed from those shot in the leg or just wounded.
Looks like a pretty good movie. Nice to see Mr. Cooper get good movie roles and not stuck counting on Hangover 1-20 for a paycheck.