I'm not sure any of them apply anymore. The government's best argument is probably, "Just because their existence was disclosed doesn't mean it's not still classified!" But, I've seen that argument before in court cases, and IIRC, a court ruled that if the disclosure is reliable enough such that everyone knows it's true and therefore it's obviously not a secret, the docs must be released.
http://www.nsa.gov/public_info/foia/