The sophistry isn't needed. If an NSA agent provides intel for use against a person in a criminal proceeding, he should have to explain his methodology, and the details of how the intel was obtained.

Consider this. Ptacek rents a car to travel from A to B. NSA/DEA/SOD tips off DPS officers to search Ptacek's car for drugs. Of course, they find drugs. At trial Ptacek's defense is "What drugs? I don't know anything about any drugs!" All the judge, prosecutor, defense knows is that you were pulled over, and you [consented, or PC was otherwise obtained] and lots of drugs were found.

Now, if the origin of the intel hadn't been concealed, Ptacek's defense atty could subpoena President Obama, sorry, I mean the SOD agent, who could testify as to the source of the intel. It might be discovered that there was no evidence to suggest that Ptacek was aware of the drugs concealed in his rental car. It might even be further discovered that hiding drugs in people's car without their knowledge is one of many ways that drug smugglers move contraband.

You completely miss the point of what it means to have a right to face one's accuser.