A few things.... One, the original report by the soldiers on the scene claimed they saw a middle-aged man throw the grenade. An addendum was added to the report three years later, claiming it was Khadr, but none of the original soldiers were responsible for the addendum. He murdered no one.  
Two... Khadr was shot twice in the back while on his knees facing away from the fight. Do you think shooting an unarmed kid in the back was something to be proud of? Don't try to paint the Americans as heros. They weren't. 
Three... Khadr was never proven guilty in a legitimate court of law because the Americans knew his supposed confession was obtained under duress, and the original report had been altered. After being tortured for years, he was told that the only way he would ever leave the Guantanamo Bay concentration camp was if he signed a confession. 
Four, the Canadian government and intelligence agencies colluded with the Americans to deprive Khadr of his rights.

These are all facts.