He was fighting with the Taliban! If he wasn't guilty, then why did he try to flee? That story about his captivity doesn't exonerate him. He wasn't in captivity from the moment he was in Afghanistan.
If he wasn't a member of the Taliban, then he wouldn' t have been in Afghanistan. He may not have been a die-hard member of the Talinban, but treason is treason.
If you're not guilty of a crime, you would not run away.