Curious that this needed to be proven, and that Google "needs" the Nexus program, as if this was a unwanted necessity.

Google has always stated that they want to run Motorola as its own entity. The companies spokesmen have always made very clear that the Nexus program will continue.

As for "fragmentation": Nobody gains anything if the Moto X ships with the latest Android version. Customers, Developer and Platform provider benefit much more from regular, long term updates (e.g. a device does not fall two version behind for two years) that instant platform updates (which are unrealistic for cross-platform technologies anyway).

The interesting question here is if the Moto X will get the Android version that Google releases after Android 5. If it is running the 2 weeks old version at release it only important for gadget geeks and the boulevard press.