Google can easily prove that they don't discriminate against white men by demonstrating that their workforce is mainly white men. There obviously isn't any discrimination on that part. There is a question of whether or not Google could discriminate against conservatives, but in the case of Damore they obviously didn't because they employed him. He could claim he was fired for political action in the workplace, but that isn't protected speech so Google were not in the wrong about that.
How he can have a case?
[1] See misconception 2 here https://www.hklaw.com/publications/Hey-Take-It-Outside-Polit...