I don't think the NSA has actually ever made that argument. There is, after all, a lot of law governing privacy. And the NSA's capabilities and required procedu

I don't think the NSA has actually ever made that argument. There is, after all, a lot of law governing privacy. And the NSA's capabilities and required procedures are also specified in minute detail. Even though these rules are far from adequate, their mere existence already shows a shared assumption that privacy is a legitimate interest. Arguing against the very idea of privacy would mean trying to prove far more than they could ever want, and doing so against essentially everyone else.