After I commented, I flagged the post. I'm not comfortable with this being on HN. FB should have a chance to fix it.
On the plus side, the entire thing may just be a misunderstanding. Other commenters are pointing out that it doesn't really live message them if you're not friends, just regular messages them -- which you could do anyway. It's just the UI appears that you are live messaging.
We'll see. But you're right -- very odd to post that here with a reward being easily available.