I'm guessing that the "attack plan" originated in one of the NSA's back rooms, and Snowden could supply a lot of detail about it, and about other red herrings and contingency plans the NSA boys have developed just in case some activity started to slide sideways into broad daylight, and they needed to do some damage control.
The NSA has been competent enough at what it does to have amassed all this information on everybody over the years. That strongly suggests that it is competent enough to have prepared contingency plans to use if any of their activities started to go bad. The only question is how extensive those contingency plans might be. Do their contingencies include threats of blackmail of elected officials or top level civil servants? If they would never go that far, then how far would they go to protect their agency, their mission, and-- incidentally-- their asses?
The NSA needs to be shut down. Its core mission and values cannot be reconciled with the values expressed in the USA Constitution.