So somebody messed up Facebook's BGP records and traffic couldn't be routed to Facebook servers. I wouldn't be surprised if some angry insider(employee) got his revenge on Facebook for whatever reason.
I'm still leaning heavily towards an "oopsie" with routing that accomplished the same thing, however.
I am talking in a very generalized sense, not for this particular issue. But I don't think the code review/deployment process is entirely safe against internal bad actors.
The whole point is to write C that appears on the level at first, but actually has a subtle exploitable flaw. The flaw is supposed to appear like a simple mistake for plausible deniability. Some of the winning responses are very devious.