I'm sorry, I don't buy this theory for a nanosecond.
I think the most likely reason that the 5D3 has the specification it has is that it is designed for wedding and event photographers. If you look at this market, the price, image quality and framerate is pretty well perfect, from what I understand.
Later in the year, likely a studio camera will come out with high MP, lower frame rate, perhaps worse autofocus.
For those with less cash (enthusiasts and amateurs), there is the 5D mk 2.
Nikon is a smaller company who don't have the resources of Canon, which is why they have to buy in sensors. Canon have already proven in the 7D sensor that they can make high density excellent sensors, and even allowing for lower yield of the larger die (dye?) it is still feasible to produce circa 50MP sensors.
Canon produce cameras for markets, in order to make money.
Is this annoying to some? Sure, but don't mistake it for incompetence. Head over to bythom.com
to read about how Nikon create great cameras, and then cannot make anywhere near enough lenses OR bodies to satisfy demand - now THAT my friend is incompetence...
"I've noted many times, supply is not meeting demand for many items, and that's a dangerous proposition as you always leak sales to competitors when that happens." - Tom Hogan...