That is one highly negative, pessimistic viewpoint, but I have to agree that he does have some valid points. I can't see that many people will have the technical skill to install Diaspora. They don't know what a server is and think that the internet is somehow magically inside their computer. Unless Diaspora finds some way to make running the server extremely simple people won't adopt it. Also they would have to educate their users on the basics of server operation. (Otherwise someone will start their Diaspora server, then turn the computer off and wonder why no one can see their profile.)
It sounds like a mess to me, and I agree that only the geekiest of people will even attempt to adopt it, and of those I wonder how many will stick with it.