Vinnl parent
I mostly agree, unless the new release modifies GPL code submitted by other entities than Google - their licensing of that code under GPL would force Google to release the rest too.
To be more pedantic here, Google doesn't have to publish anything anywhere.
According to the GPL, the only thing they would have to do is provide source code to the users of their software upon their request.
True, though I doubt that would've happened either (possibly it would have sped up this publication).