I hope one at the end of his political career, by choice, might push ahead anyway. He could announce something like Yes, I did blow and hookers, five years ago. But the NSA does this pressure for silence to so many more people.
In today's political climate, there's more than a passing chance that a politician who is not at the end of his or her career could survive the average scandal more or less unscathed, while the damage to the NSA would be catastrophic.
I could easily imagine someone coming out with "Yes, I was banging the intern, and her sister - that's totally true. What I did was wrong, and my wife may never trust me again - we're going to work through that. However, check out the incredible ramifications of this dossier being held over my head in order to coerce me into silence!" - dude might pull off the scandal, or he might not - that's a D20 roll on his charisma mainly, but definitely a non-zero chance. Over in the blue corner, on the other hand, you've got basically no saving throw.
I think this is more or less true. I also think that the NSA can wield plenty of influence without resorting to something so risky. They have a lot of support among the political elite. This administration has their back and I bet the next one would too, whichever party wins in 2016.
But what if they are threatening relatives or other persons you care about? There might be choices where you are not the (only) bearer of the consequences.