The timing of going to NLRB made it look like emergency maneuvers to me. If I were him, I would also have copied e-mails and forum posts like crazy, but I am wondering what the level of security at Google is.
He's a master chess player. My mentor Program Manager once told me, to work as if I am playing chess--understand the objective and plan a few moves ahead. It helped me tremendously. I am sure he has plans for "Google starts internal discussion" and "Google fires him" scenario.