I think you're fundamentally misunderstanding the way these kinds of things happen at Google. Most projects of this nature have to work to get internal adoption just like any external toolchain. There's almost never an "edict from on high" that a project will use a particular technology (except to the extent that most code in production has to be written in a set of approved languages; a language created by Google itself still has to surmount this hurdle).

Pike, along with other Go team members, have been heavily involved in solving very large-scale problems (e.g., http://static.googleusercontent.com/external_content/untrust...) for a long time now, so they are solving the pain they've personally experienced. But other teams at Google will treat Go just like developers in the world at large do -- with skepticism, until it's proven itself. It's doing so now, but it will take some time before you see heavy adoption, which is the way it should be with any new system of this magnitude.