At most 8% of the prisoners Obama has released from Guantanamo have gone into fighting the US. On the contrary, many of the prisoners have become rather magnanimous, given the circumstances.

The issue is a distraction anyway. If someone did fight for the Taliban and was captured, he ought to be treated as a prisoner of war (thus, kept in Afghanistan). If someone planned or committed crimes, whether terrorist or other, he deserves a fair trial.