Unfortunately, his posting comes off as a bit smug and superior for my personal tastes. Though I have tremendous respect for Craig's ability, this posting comes across as a "shut up you naughty children, you're not as smart as me and Apple so you can't have an opinion on this". It is definitely true that he has first-hand experience that most of us don't, but since the decision he's justifying is one that prevents us from gaining the very experience he's claiming we need in order to have an informed opinion (without jailbreaking our phones, at least), I'm finding the argument a bit circular for my taste.
To work with Craig's own metaphor: Don't cut off our hands to keep us from shooting ourselves in the foot. Some of us idiot developers who are apparently not smart enough to have an opinion on this, might just surprise you by finding a way to work around the problems you encountered. Or, just maybe, our applications have different background processing needs than the one application you've tried this with. Since Apple has set themselves up as gatekeeper to the App Store, and since no self-respecting developer is going to ship a product without testing it extensively on a real iPhone first, I don't see the need for such drastic exclusions from the SDK itself. They could control this by subjecting apps that use background processing to greater scrutiny, or providing a sanctioned mechanism that can enforce limitations, not by making those parts of the iPhone completely verboten.