There are layers of stupid in objections to Facebook but "something something watching your cameras" is by far the dumbest.
Not only does the Oculus positional tracking camera not work like that (and can't work like that since you know, you have an Oculus Rift on your face) but no one has managed to give a statement on what they think the value of that data would be.
Uh, I can think of useful data analysis to run on that.
Both to characterize the feelings associated with relationships (which is data that Facebook would like to know), and sentiment analysis for various adverts or other things.
For example, Facebook could use a virtual room for people looking to interact, and then place ad objects within the room - and rate your responses to them, in order to profile you for advertisers, and figure out what kind of placements generate the least interruption or most positive association.
Further, you're only talking about the current gen Oculus technology, and not anything about what Facebook might (speculatively) deveop going forward.
The obvious path (seeing other virtual worlds) is to generate some method of putting realistic gestures in to the experience, which I highly doubt they'll never attempt to do.
I'm much more okay with a stand-alone thing doing that, than anything tied to Facebook's environment, because I believe Facebook is a fundamentally exploitative company.
The Oculus camera doesn't work like that right now, but the social-related uses Mark Zuckerberg has been talking about for VR definitely would require facial expression tracking.
Not only does the Oculus positional tracking camera not work like that (and can't work like that since you know, you have an Oculus Rift on your face) but no one has managed to give a statement on what they think the value of that data would be.