Interesting comment in the RPS article, from someone who claims to be a Maxis dev:
So how difficult would it be for EA to create a single-player game that simply did away with the multiplayer-derived aspects and just let us build? It seems that lies somewhere between “easy peasy” and Bradshaw’s claims of “significant engineering”. According to our source:
“It wouldn’t take very much engineering to give you a limited single-player game without all the nifty region stuff.”
So if this source is good, than it really is all about the region stuff. Although the Kotaku article says he was sending and receiving region commodities while offline. Go figure....