Not if he is an actual combatant. One can be a combatant without picking up a weapon, or participating in an actual/successful attack.
Then ANYONE is a combatant!!!! Affiliation with a group is not a crime. Actions are crimes, not affiliations.
I am against abortion and support pro-life causes, therefore I am guilty of captial murder because someone else with my beliefs murdered abortionists.
Because some in the KKK lynched blacks does not mean that everyone in the KKK is guilty of that crime.
Nate Newton got busted with 100kilos of ganja. Therefore all of the Dallas Cowboys should be locked up.
I was a Naval Aviator in September 1991 and at Tailhook, therefore I am guilty of sexual assault.
When he was originally detained, they had no intention of treating him as a combatant, until they realized they had no case. Why was it the customs service that nabbed him, rather than some security agency? He is a citizen, and on US soil. Hating America is NOT a crime. Receiving training is not a crime, affiliating with a private orgainization is not a crime. This is why he has to be held without rights - because he committed no crime. I have received training on how to smuggle drugs, dodge taxes, kill people, covert communications, and how to use airplanes in many a nefarious manner. If I suddenly hated America, would I be a combatant?