Or they could say they were monitoring Maddox, when in reality, they were snooping on someone else, or just mooching server space to use in a distributed network they were running. You have no idea, and neither do most people working at the NSA, or the FISA court, etc, etc.
For all anyone knows, this "monitoring equipment" could have been hosting (and let me just go for the Godwin Gold here) a child porn darknet for a ring of senior paedophiles operating inside the NSA. And if anything went wrong, or was discovered, the NSA could ahve just pinned it all on XMission, Mr. Ashdown, and his attorneys. After all, there's no official record, all are gagged from revealing what they know, and the NSA would just lie about it.
And in case this seems hyperbolic: If the NSAs programs continue for long enough, this will happen. History is the definitive proof.