However, technology moves fast and expectations grow each day. I don't think there were that many expectations from Gates or Zuckerberg as much as people expect from these guys. Maybe they'd be better off getting outside help. At some point of time, MS and Fcbk expanded as well. Diaspora needs more involvment (not opensourcey but someone working fulltime on board with them) much sooner than those cases.
Have you met them and talked programming or is this just hyperbole and conjecture?
They were out at the Web 2.0 Expo Startup Showcase http://blog.web2expo.com/2010/07/get-your-fledgling-company-... and in the conversation I had with them they seemed very passionate about Diaspora the project.