It's amazing to me how many people want to find a reason to hate Jonathan Blow, just because he uses twitter.
I've been following Jonathan since Braid was announced, I've seen every single lecture he's done on video game design, I've read all his blog posts about how he programs and develops and everything else he's written. I've been part of the Braid speedrun community and I've seen how deep the game really is, not because of the story, but because as a game it has depth. I've been following The Witness since it was announced, and read every post on the development blog. I think I know Jonathan as well as a person who hasn't met him could.
That said, I respect his opinion on game development more than any other dev I know of, and he has good reason to be suspicious of Microsoft.
Really, imagine lighting being calculated on a cloud server. There would be, at minimum, 100ms delay roundtrip if you have a decent wired connection and live close to the servers. If you live somewhere with high latency, or you use wireless internet, that delay could easily go way up. If your connection drops in the middle of a game due to your router or ISP or any other issue, what are you going to do, have no lighting in your game? The cloud will be good for storing your game saves and other data, hosting game servers, and that's really about it.
Even Sony's Gaikai is questionable, I can't see it being much better than OnLive, which, frankly, wasn't good enough (I've tried it myself)
Anyways, I really don't think people should be reading so deeply into Jon's tweets. It's just twitter, a place where you casually type out 140 characters.