My NSA-induced paranoia level:

Same for NSA; they *can* blackmail you, but the chance of them doing this to YOU, specifically, are very, very, very slim.

And yet, anyone who has a second thought about going into politics because of this potential, however slight, has had their First Amendment rights infringed. Ditto for people who have ignored friend requests due to the potential for guilt-by-association. (Now that we know they're going as deep as three hops, not only do you and your friends have to be politically reliable, you have to ensure that friends of your friends are also politically reliable.)