Maybe I'm being stereotypical here, but not only is this a well-executed hack, it has well-written copy. Which is not standard for malicious hackers looking to make a point.
The Facebook statement isn't that good. For example, this wording...
While we generally are sensitive and confidential with respect to employee matters, the situation has taken on a public nature.
...is extremely unlike the words usually used by a company dealing with a controversial employment matter. It's more like the puffery used in 419 scams.