I think if NSA gets shot down, which I agree it should not, it will be on the theory that FISA prohibits any intercept for any purpose of any call originated by anyone anywhere in the world involving one U.S. phone line without getting a FISA warrant. Similar to the rather tortured reasoning Kennedy used to say the UCMJ prohibited the GITMO tribunals.
Like you, I just don't see how the Fourth Amendment could be flogged into prohibiting the NSA program as "judge" Taylor asserts.