Don't get angry, get a patent! That's probably the rationale Facebook is using with regards to IP rights ("We don't like the idea of patents, but we dislike even more the possibility of a patent troll extorting us for something that should be obvious, so lets act preemptively and file for a patent").

Defensive patents don't stop trolls. That's the whole point of trolls (or Non-Practising Entities), you can't counter-sue or cross-licence, you either pay lots of money to win the court case or you pay lots of money to the troll.