In my view it appears that Canada's black eye has largely disappeared from the public's mind and now it's the US military justice system that looks bad to the world.

...Do I think Omar Khadr is responsible for his upbringing? No.
...Is he responsible for his own actions at age 15? Partly. At that age, though, inexperience and hormones cause many a poor judgement, though I don't know what "better" judgement he should have made at the time, given his upbringing and being in a war zone.
...Do I want him, considering that upbringing and life experience, to be my neighbour, my niece's schoolteacher, my gas jockey or grocery store owner, free to do what he's been raised to do? The honest and embarrassing answer: Probably not.
...Can he be rehabilitated? I have no idea.
...If a 15 yr old white Canadian emigrant to Afghanistan raised by war mongering parents named Smith or Jones had thrown that grenade, would the Canadian gov't have behaved more supportively to him, stepped in more forcefully on his behalf? Sadly, I do believe so.

In any case, I supposed that I'm just another small-l liberal who is awfully glad that someone, somewhere gets paid to make various difficult decisions (like whether to lobby the US to reduce/dismiss charges, like making a personality or psychological assessment of the guy for court, or decide what his punishment should be, etc). I don't know that I would be any good at it.