The US judgement was never going to be enforced in Canada.  The plaintiffs admitted as much when they received the award. Like it or not as someone under 18 Omar was a child soldier and no Canadian court would of upheld and enforced the US judgement.

Then there is the reason that the US used military tribunals instead of the US courts is they knew that they used illegal methods to collect convessions and evidence that would not stand up in regular court of law