I have a couple of theories on why Google came down on James Damore like the proverbial ton of bricks.
Why there's a crackdown on anything that looks “alt-right” now
The tech industry top people don't actually like feminists (who have a tendency to produce expensive lawsuits) but they made the mistake of surrendering to them (at least verbally) a decade or two ago and it's too late to go back now. They have resolved to not let that happen again.
Meanwhile, opponents of feminism (or left-wing ideology in general) have been saying it's time to imitate left-wing tactics. As a result, the tech industry is trying to stop Feminism II before it starts. It is, after all, very difficult to surrender to two incompatible factions at the same time.
Without the threat of the imitation leftist tactics, disagreeing with company dogma would simply earn a reprimand and a warning to not do that again. With that threat, dissent produces:
JUST DO NOT DO IT. DO NOT DO ANYTHING SORT OF LIKE IT. JUST AVOID THAT ENTIRE CATEGORY OF THING.
The infamous memo might not be “alt-right,” but it can be plausibly claimed to be in “THAT ENTIRE CATEGORY OF THING.”
Was this a false flag?
A conspiracy theory I haven't seen anywhere yet:
Since Google has not actually been promoting that many women, it doesn't look like it is a real feminist-run organization. What if the purpose of coming down on James Damore in such a heavy-handed manner is to provoke such a lawsuit? They might be able to get a court order that they can wave in the faces of the feminists.
If the lawsuit goes the other way, of course, they now have a legal precedent that can be used to fire feminists suing them.
I (and apparently very few other people) noticed that, with a few minor changes, the Zunger response to the Damore memo (including the need to fit in) could be used against feminists.