Why should it be so hard to believe that this is actually a 5D III prototype ?
Why should we go to such lenghts to debunk it ?
It's safe to say that by now there should be many such prototypes around in the hands of key photographers, and Kai could very well be one of them.
He definitely seems to have a strong affiliation with Canon.
( http://cpn.canon-europe.com/content/interviews/pfaffenbach.do )
Regarding the upcoming Olympics, the IAAF Championchips seems like a more than an adequate place to try out the new camera bodies.
I fail to see any other plausible justification for covering the logos on the camera, especially since Kai is a Canon endorsee.
The similarities of this body with the 5D II are evident, but we actually don't know how the Mark III will look like. It could be very similar. Also as it has already been mentioned, what's on the inside is what really matters.
I sense a future Mark III here...