What Damore may be trying to do is establish a legal understanding that the political discrimination (which definitely happened) was connected to racial discrimination (which would need to be proven in court). If Damore can do that successfully, he should be able to win the lawsuit.

But I don't think it's possible. At least it shouldn't be possible. Like you suggested, companies must be able to discriminate against political behavior at work that is disruptive.

Damore's memo was released in an unruly manner that disrupted Google's bottom line. It also brought down company morale, alienated fellow coworkers, and caused undue internal strife. His resulting unwillingness to help contain the drama demonstrated his lack of allegiance to the company's interest. Behavior like this cannot be protected from termination.