Yeah, I can see how one can read it that way, but doesn't that go without saying? How many games require more than one controller? It's an odd way of phrasing it. A more appropriate way to say it would be, "WiiU will support multiple [tablet controllers] but we are not planning on releasing any games that require more than one. There will always be an option to use the Classic controller for multiplayer games as we do not want to force our consumers to own more than [the tablet controller] that comes with the console."
What it sounds like Iwata is saying is, "WiiU is perfectly capable of supporting multiple [tablet controllers] but we are not including this functionality due to cost," which, let's be honest, is total bullshit. I don't need to own 4 Wii remotes (and I don't), but I can if I want and it's certainly very expensive especially when coupled with nunchucks. Nintendo never asked anyone to invest that much money. However, the possibility is there and Nintendo let the consumer decide.
I remember reading how Nintendo originally didn't think of the nunchuck for the Wii and that the idea came from Retro Studios. Apparently, they seriously considered the Wii remote without the nunchuck. Holy lack of foresight, Batman. That said, and if Nintendo is currently planning on not supporting multiple tablet controllers since the quote is rather unclear, I hope Retro or any number of 3rd parties steps in and explains why that would be a terrible idea.