Not to go off topic, but was Epic Yarn bland? I haven't played it, but it looked very good to me. Also, I think those are two different teams. Mario is EAD and Kirby is Hal.
But you make a good point; nintendo doesn't really have as much experience with this sort of level design. On the other hand, the game sounded like a fairly slow platformer. Two of the colors were described as being quite slow. I don't think sonic team has put out something like that in a long time either. Billy Hatcher maybe? So it is feasible. We also don't know what the development time table would be, nor what development on the wii u is like. Nintendo may want a launch game, and is sending over people more familiar with the technology. All this, of course, is indulging the ridiculous notion this is true.