Internal blog posts written by Yegge earlier didn't leak afaik. Incendiary technical posts written by people in positions of power didn't leak. I mean, not even hints of them, let alone the full text. Maybe the engineering culture has dramatically changed in the last few months, but it used to be the case that full copying of internal technical discussions to external forums would have been totally unthinkable.
Especially one where he pretty much writes that Google's #1 is not 'Steve Jobs'.
Really, I think that no matter what that this would have found its way to the general public somehow. That said, I think it's great that he speaks his mind like this, even if it is intended for an internal audience only.