I wonder if it has anything to do with Pokemon? Or rather, if the delay will actually end up helping Yokai sell more units.
I know that both series can co-exist, Nintendo wouldn't advertise Yokai so much otherwise (they even had a Yokai in a NoA Mario Mountain Ski video)
But I bet that it might help the software sales in the short term. Although it is noted that not releasing during the holiday affected the sales of merchandise, so maybe it wasn't worth it in the end.
Of course that's mostly assuming that employees aren't leaving. If they are, there's nothing they can do about it but delay the game. I'm guessing that the employees weren't being treated properly.