Because he's a weak-minded moslem freak.
His mental state and evil act is way beyond trying to comprehend to put them people through and then lie down and expect to get treated humanly.
But to speak to the frustration of the circumstances in which our Troops have to work point for the Iraqi Military and Syrian rebels with rules of engagement favoring the enemy, not knowing who is the enemy, the enemy within fighting with foreign forces, may be at a very high level of battle fatigue for those who have endured. Thanking them who have served and do the best considering the way the deck is stacked.