Omar Khadr video released

My eldest son is 16 years old. I watch this video, taken during interrogation of Omar Khadr when he was 16, at Guantanamo, and I weep. Omar Khadr is now 21 and only just coming to trial (such as it is in our GITMO system). He’s a Canadian citizen. Here’s a RollingStone profile of him from years ago.

Even if he's guilty of everything they say he is -- and I seriously doubt that -- why couldn't we have AT A MINIMUM treated him as the juvenile he was when he was arrested?