Not defending anything about Guantanamo here… The entire place is bullshit.
But at the same time it looks like he was repatriated back to his own country… And they sentenced him under their own laws. The gitmo shit technically has nothing to do with Algeria courts and law.
The US doesn’t really have a say with that. They can make requests, but ultimately it’s up to Algeria. Just like if the US receives a citizen/prisoner back from say Russia that committed US crimes, no matter what Russia may have promised them, the US has the right to charge them under US laws.