Agreed, 5.56mm drops like a rock at about 250 meters. I think that the sniper didn't use a BDC (bullet drop compensation) calculation with his shot. His oversight probably saved the boys life.
Semper ARMED AND DANGEROUS!!!
According to reports, this was a chest shot, and IIRC the MO is to go for the body, not the head. This doesn't sound like an oversight -- merely that he aimed as desired, but didn't get the kill.