Your demand for evidence and facts is bogus, since there cant really be any. What we are talking about is what goes on in the mind of an individual. We cant prove that. But we do know that, for want of a better term, implied pressure to conform works. Its the same reason belief in a god works. God knows all and will punish us if we don't follow his rules. So, if we believe in the god/NSA, we do what is wanted because we don't want to be punished.
We know people act like this. We know it is possible that the NSA has information that might damage us, or ones we love. We know what the NSA wants. Therefor we have reason to believe someone who might want to control the NSA won't out of personal fear.
A reasonable deduction, based on what is known and history. No, sorry, no evidence. That one of the nice things about blackmail, there usually isn't because the victim obviously doesn't want to be outed.
Yes, of course the elected officials are victims in this, potentially. But as elected officials, with the power of democracy, they are, IMHO, duty bound to put that aside. Not doing so is selfish cowardice. Some one has to be as brave as Snowden, and I don't see that in our elected officials.