What about the threat of the agency who secures the system simulateously compromising it in order to gain blackmail material on its user?

In that case, I'd worry about the user doing unlawful/immoral things they can be blackmailed with. Agencies have made up accusations and set up traps for politicians in the past (and worse: see FBI vs. Martin Luther King, Jr.). If they can blackmail a person with the truth, chances are that others can do it too (criminals e.g.).

conspiracy theory.

Isn't one of the main arguments against dragnet surveillance the possibility for the surveiling agency to blackmail the politicians who write the laws limiting its power?

The same argument surely applies to targeted surveillance...

sure. i was aiming to poke people citing occam's razor when controversial matter comes up because cognitive dissonance or whatever their problem is. sheep like to chose the easy path of denying things like you suggest ... until snowden gives up his life. and still they go about their useless business.

but after all, it _is_ a conspiracy theory because there would be at least two parties involved conspiring to blackmail. sheep also don't get what the term actually means.

Isn't it possible that there is sometimes conspiracy fact? That something is a conspiracy theory doesn't automatically invalidate it.

correct. you've got it.