This is a tendentious statement, so I will relate my own experience. Once upon a time I was working in California, at a tiny startup, and was reading some election results from "back home" in North Carolina, which had just passed Amendment One by about a 3:2 margin. Observing the results thoughtfully, my coworker casually remarked "wow, 60% of North Carolina is literally horrible, terrible people."
I just quietly sat back and thought "why, how nice of you, sir, to refer to some unknown fraction of my family and the friends I had growing up in such a lovely manner."
At one point my girlfriend (now an ex-girlfriend) attended a party that he was hosting. She had just left Missouri out of disgust for its Missouri-ness, and was very much in love with San Francisco and its people – yet left the party modestly offended – not for saying anyone in particular was bad this time, but just with all the best of intentions saying it was inevitable that they'd all come around to the modern views on things like gay marriage (and, in the process, utterly trivializing their religion, values, and world-views).
I do not seek to cast him as a bad person for this remark. This is a man who, if anything, is one of the nicest people I know, easily far above the average, and a quitessential San Franciscan (well above and beyond your typical tech hipster). But he is immersed in a culture which specifically and explicitly denies human dignity of people who are not alike and do not think alike.
This is very sad. You would think if there is one lesson we could take from the history of the US, religious tolerance in the colonies, slavery, the Civil War, the Civil Rights Movement, our wars with Native Americans, the likes of the Japanese Internment, women's suffrage, everything ... if there's one resounding strain here, it's that you don't un-people people.
(but it's okay to un-people these people, because they're bad people!)
In conclusion:
I sympathize with this guy who wrote this manifesto. It is also unfortunate that, from what I hear and understand of the matter, this guy is factually in error, probably sexist, and almost certainly undermining his cause.