I am really wondering, have you actually read the manifesto?
Because non of the things you are writing about there stated in the document. The author did not say that woman were biologically worse at being engineers but that there might be biological factors which could explain why we do not see a 50:50 ratio in the workplace.
He never wrote anything about individual people but about distributions for a hole population. Would you regard the statement: “On average, men are taller than women” as alienating towards tall woman or small men? No, you would not.
As you seem to be on the more sensible side of things, please, read the manifesto before writing about it. There are already enough people who haven’t read it and yet obviously know who is in the right and in the wrong (and that includes both sides of the argument).
Full Disclaimer: I am a male Physicist, not living in the US or working for Google so besides my gender, I do not have a horse in this race. Also not a native English speaker so please excuse if i made some stupid mistake writing this. My main concern is not so much what google did with this engineer, thats for courts to decide, but how the media presents this issue. At least in my home country, most (if not all) of the articles about this topic are basically “Male engineer fired after writing shit about woman”. After reading the manifesto, I do not see this articles as being true so either a lot of people writing about it haven't actually read it or are actually trying to misrepresent it. Both is devastating for the trust put into the media.
Well, at least that is my take.