The part that falls under "so on" is the scary one. From the article: "NSA reportedly is making a copy of nearly every international email. It then searches that cloned data, keeping all of the emails containing certain keywords and deleting the rest – all in a matter of seconds."

Note the weasel wording: "certain keywords". You don't know what those keywords are. You don't even know what topics they happen to cover. Once you somehow become flagged for suspicious activity, the NSA can go back in time and see everything you have said about _all_ of their "suspicious" topics. You are now an even bigger suspect.

And once you are a suspect, anything and everything in your past can be interpreted in the light of you seeking to commit the questionable activity. Thanks to NSA storing only the material that matched their keywords, they now have a stash of incriminating material that has a very strong selection bias.

I'm pretty sure even Franz Kafka would have been proud.