Yeah, the CEO of a company saying numbers on official communication to investors is pretty compelling evidence on its own, especially if it's bad news. Executives don't generally lie about specifics to their investors, unless they're doing something completely fraudulent. And if you think that's the case for Facebook, you're going to need more evidence then just a gut feeling.
Not to mention supporting data for announcements like these tend to come up in discovery requests for lawsuits so I highly doubt they'd make such a definitive statement w/o the points to back it up.
