I'd be more worried of the people on Facebook. Retards the lot of them. It's not that people not on Facebook have anything to hide; it's the fact most people on there don't mind sharing every little detail of their life on there, most the time with no real relevance to anyone. Maybe the other people just don't feel the need to gossip or lurk/spy on others. I think if you examine Facebook closely it isn't really a very good social tool, and it may cause more social discohesion (yes, I'm inventing words) by simply using it.
And I'm sure the article neglects to balance out the retard factor; cyber bulling, resulting suicides, marraige breakdowns, job losses, the antisocial side of facebook etc.