I think his point is that if you are using Facebook, you are still limited by the level of trust you have with them. That should be quite low for any privacy conscious internet user. That you are using a different IP and a pseudonym might be a hoop for them to jump through through to figure your identity out should be considered in the context that they are likely already collecting data about you without your consent from many different sources. When it comes to jumping through these kinds of hoops, Facebook is a circus lion.
Obviously if you log into a Facebook account with your real-world identity then all actions performed on the site will be linked with it, but that is expected.