It was right to release Jamal al-Harith from Guantanamo, because he was charged with no crime. The fact that he subsequently joined PISSI can't change that.

17 Britons were prisoners in Guantanamo and released. Here's what happened to them.

One of them joined PISSI. But if he hadn't been imprisoned, maybe he wouldn't have done that.

One of them simply lived peacefully, but the way prison had maimed him provoked his nephew to join al-Qa'ida. We can be pretty sure that, if the US hadn't imprisoned people without charges and tortured them, he would not have become an enemy of the US.

There are surely hundreds more, if not thousands, who were inspired to fight the US by their disgust for Guantanamo.