He was fired for effectively casting doubt on whether his colleagues were qualified for their work or whether they were just hired to meet diversity quotas.
And why is that wrong? Worrying about your company's hiring bar is a very normal thing. HR should have contacted him to explain how they balance the desire for diversity and the desire for hiring the best candidates. There's no need for a public execution.
Policies that are effectively affirmative action are by definition lowering the bar for diversity candidates. His statement that it can lower the bar is correct but still not something people like to be reminded of. Google (and others) not recognizing this distinction and treating his lack of discretion as hate speech is irrational mob PC rule or just plain cowardice (if he was fired for PR reasons).
"His statement that it can lower the bar is correct"
In an n-dimensional space where we take into account all the factors that go into whether or not a candidate is given an offer, you're actually complaining about "lowering the bar" when the bar is already lower for people (for people that's not being targeted for affirmative action) due to systemic effects? You're actually complaining that we're lowering the bar by tweaking other variable so that the bar will be effectively the same obstacle for everyone?
Or sued, seems like this would be an easy basis for a hostile work suit. Couple promotion denials, a documented complaint and this manifesto would probably be an easy lawsuit, though INAL.
I don't think that's what he means. I think he is saying they are qualified, but many qualified people have also been excluded based on gender or race (i.e. the "false negatives" that gets repeatedly left out). For all he knows, those same people might have been the most qualified, but much of the competition didn't (allegedly) get a shot to compete against them.