This is really getting extremely tinfoilish now...
I can think of multiple examples where this sort of thing has happened already.
Its no different to me recording a conversation/video of somebody without their knowledge and then using that conversation/video against that person in the way you describe. I could even do it with their personal emails. Heck Ive lost count on the amount of times Ive heard stories like this on the news.
The only difference? Somebody in power will have the surveillance/email. Is that really a threat? No.
Ummm.... Given recent history, I suspect that a fair number of citizens in a fairly long list of countries (including Russia, Poland, Hungary, Romania, the eastern bit of Germany, Egypt, Iran, China, Cambodia, North Korea, Cuba and Zimbabwe) would probably dispute that claim. And with good reason.
Surveillance should only be carried out under a tight regulatory framework (where the default is a presumed right of a citizen to privacy) , properly authorised under reasonable suspicion and with independent oversight. Anything else....... well that road is well trodden, and you can see where it usually ends.