A better example is an atheist working with an evangelical. Both the atheist and the evangelical will have very strong opinions on each others' belief systems.
Will the Evangelical write a 10 page memo "explaining" why there are naturally fewer Atheists in his profession because their biology makes the inherently less interested in it?
I'm actually not surprised that he got fired, and I do think the firing is justifiable. Writing open manifestos against company policies on controversial and sensitive issues is going to get you in trouble. It just will, whether you're at Google or 'Dave's Grill-house'.
But that's not what I was responding to. OP implied this guy is a racist or a misogynist and stated she couldn't work with someone who held his kinds of beliefs.
I've read the manifesto and it's not as strong as you make it out to be. For example, I've argued that you can't expect perfect proportional demographic representation in a free society in any field. It will not happen, for a variety of reasons that may not be nefarious. If women are under-represented in programming it may not be because of sexism.
A better statement would be: "Will the Evangelical write a 10 page memo "explaining" why there are naturally fewer Atheists in church organizations because their beliefs makes the inherently less interested in it?"
The answer would be yes. But it's not a good example.
My argument is that one's religious beliefs dictate what sort of organizations one will be a part of, just the same a person's physiological makeup will dictate his profession of choice.
I'd like you to more closely read the thrust of his memo. His main thrust is that Google should review their processes and see if they can't create a workplace that the average woman would like to work in (taking as inspiration the average personality tendencies of the average woman), without resorting to sledgehammer positive-discrimination policies that target women because they are women.
As a thought experiment, imagine a company reviewed their processes to create a workplace where the average black person would like to work.
It's kind of offensive to be judged by this hypothetical "average X person" stereotype. It more or less implies it's their fault, that they are underrepresented because they want to.