Did you RTFA?

This is just providing a view of Stack Overflow that's limited to Facebook questions, and Facebook staff providing more support there. Facebook has been a login option for Stack Overflow for a long time, but don't even require you to even make an account to ask questions.

Of course it doesn't mean that, but even if it did, what user data are you talking about? The only non-public info that Stack Overflow has from (some) users is their email address and real name, which Facebook already knows.

But facebook can't associate Real Names with questions asked on stackoverflow.

If they had data-sharing in place, they could.

Oh my god, Facebook will know that you asked a question on how to write Hello World in lisp!