...U.S. citizens as well, it's just that the Courts had ruled in the past that they clearly had jurisdiction. And the interpretation that you cite is just that, an extra-judicial interpretation that has not been ruled on by the courts (at least not yet). Article III of the Constitution does say that:

The judicial Power shall extend to all Cases, in Law and Equity... between a State, or the Citizens thereof, and foreign States, Citizens or Subjects.... The Trial of all Crimes, except in Cases of Impeachment, shall be by Jury; and such Trial shall be held in the State where the said Crimes shall have been committed; but when not committed within any State, the Trial shall be at such Place or Places as the Congress may by Law have directed.

Add to that the fact that foreign citizens on U.S. soil have been granted the same rights to trial (like the shoe bomber), and that Gitmo is currently under U.S. supervision (i.e. it is effectively a U.S. territory), and I think the interpretation is on a shakey foundation.

But, in the case that the packed Courts do say that detainees of the U.S. government do not "deserve" fair trials, I still think it makes a mockery to hold such kangaroo courts where the evidence is not put forward and even the names of the detainees is "secret". The real issue is that the U.S. has detained these people for three years and has shown no inclination to produce public evidence to support this detention. Hell, if the Supreme Court had not said that the detainees could challenge their status as "Enemy Combatants", even these feeble attempts at hearings would not have taken place.