I thought Google was the one who delivered updates to official Nexus devices, not carriers?
Depends on how you bought it. If you bought it directly, it's from google. If you bought one from a carrier that sold it without futzing. It's from google.
Some carriers, around the world, opted to futz with the phone and the updates are dependent on them. This was the case for even some of the Nexus Ones.
Basically they only way to guarantee a google update device is to buy it unlocked, retail. (even then it's a crapshoot since Google doesn't like talking about products you pay for.)
The Nexus S update started rolling out to the T-Mo Variant, but it was pulled. Same thing for the Sprint Variant.
Regarding that vergecast about touchwiz: I only sat through about two minutes of it, but those three guys came off like real douchebags. "Oh nos, someone likes something I dont!".