I haven't read the manifesto, so I'm not saying it is anti-diversity, but your post appears to assume they can't be lying or wrong about that.
I have. The response labeling it "anti-diversity" is a pathetic and dishonest attempt to dismiss the entire thing. The "manifesto" is an honest attempt to start dialog, the shrill propaganda from the likes of Gizmodo and Recode are dishonest attempts to drown out that dialog with name-calling and rhetoric.
They can of course claim technical correctness by equivocating about what they mean by "diversity" but it's not like anyone reading that filth really cares about what words really mean. You could say it was "anti race and gender diversity for diversity's sake." You could say it was "anti race and gender diversity as religion." It's opposed to taking inequality of outcome as ipso facto evidence of discrimination.