I think that means Vodaphone can put some kind of "hold" on your firmware, much like is happening here in the US. The Euro case is "interesting", because if you go to nokiafirmware, you can see the firmware, and download it (if you want it enough to NOT do an OTA update).
I have a completely unbranded 950XL (this phone was never carried by a single carrier in the US), yet it would appear that somehow the US carriers have a "deal" of sorts, where they can hold the firmware (from being published yet even) while testing is done. I kind of wonder if this is legal, but it probably doesn't matter, given the number of people affected.
I get the DOS type of thing, and whole works (I've written tests for similar, not on phones, but other OS components), but if it's good enough for the Euro carriers, which aren't exactly tiny, why would the US carriers not accept the testing done? I'm sure there's a full set of regressions run against this, having done a lot of OS work myself.
The ONLY case I could see this being valid, is if the carriers here discovered a flaw in their networks, and needed to review things before release.
Makes me wonder, I've never heard of a unbranded Nexus release being held up by a carrier?