Are you saying that someone who plants ied's is automatically a terrorist? I guess that makes many soldiers in war terrorists then. It is a common practice in war. It has been since chivalry died during WW1. 
As far as the incident when he was caught. You might remember Khadr was under fire and did as anyone might do, including maybe you, he retaliated with what was available to him. I have great sympathy for the soldier he killed with the grenade but it was a moment that only those who have been in similar circumstances can understand. Have you been at war moon?