I've no doubt that it can run like that (and given SimCity works for ~30 mins or so without connecting to SimCity's servers, it's no shock to anybody who actually played the game at launch); but that doesn't mean that their intent when conceiving of the game wasn't for the online aspect to be utterly central and integral to how they wanted people to play the game. The always online "requirement" could absolutely have resulted from that desire rather than DRM.

If it was just a matter of DRM, then it's plain inconsistent with how they're approaching DRM with every other PC release they've done recently.