If al-Marri and Padilla don't have any rights that the government is bound to respect, then neither do you and I, folks.
Hence, the case at hand involves -- and we limit our analysis to -- persons seized and detained within the United States who have constitutional rights under the Due Process Clause.
This guy wasn't picked up on a battlefield. There's no reason why the charges against him can't be proven in court just as they would be for any other wrongdoer. I don't know why we're so terrified of due process; we have a great Constitution and we shouldn't be ashamed to try people under it.