I've read the memo in its entirety.  Obviously the writer is sincere, although clearly "out of his depth" as to the subject matter.  He puts a scientific facade on his argument, but that rubs right off as soon as he starts polemicizing about being a disrespected conservative in a "leftwing" company -- because it becomes clear that this is his true underlying issue and diversity is simply a convenient hook to hang his grievances on.

The workiverse is full of opportunities.  He can find a workplace that's a better cultural fit for him, or he can do as Page and Brin did and create his own.  Of course, he can also try to change Google from within.  But releasing a ten-page memo attacking a core company policy may not be the most personally prudent course of action.  He shouldn't be surprised if he now has no recourse but to find other employment.  Choices have consequences.

There's no such thing as 1st Amendment rights in the workplace.  Conservatives can hardly argue otherwise.