well for one thing I'm British. I agree that it's fair game for companies to seek to remove people who are actively hostile to other employees but from what I've read about this memo (admittedly I haven't read the original itself) it seems like he wasn't saying "quick, fire all the female engineers!" but more like "Google's diversity initiative to get equal representation amongst male/female engineers is nonsensical because women are on average less likely to become engineers due to natural temperament differences in men/women". Maybe I haven't bought into the ideological argument but nothing there seems particularly contentious, nor does it seem like he's saying women shouldn't or can't be engineers.