Jobs was pretty notorious for this kind of thing. There's another video where he said no one would want to watch videos on an iPod like device. Next year Apple shipped the first iPod that played videos.
That and he's dead now so who knows what Apple would be doing now if he were still alive. For as much praise as he gets, there are a lot of insider stories where he was terribly wrong. Another famous one is that he didn't like the name iMac initially and almost chose MacMan instead.
He might have been better than average at picking winners, but I think his true talent was that he had a good eye for other talent. Apple didn't succeed because of Jobs's vision, but rather because he put a lot of really talent individuals into a position where they could make Apple succeed.
He said those things, but I bet you in the back they're designing prototypes experimenting with different screen sizes. I bet you even if Jobs was in charge today, we would've seen a larger iPhone 6. Even if he's vehemently against 5.5" maybe it would've been something less large. But there's no way Apple would get away this time around with a 4" screen still.
In the end I think Jobs was a troll. He made bold statements that often seem shortsighted or just outright rude. It's like some members on this forum here. But i think he knew what he was doing with the company in the end. It's just bad press, but the press tends to ignore these about faces anyway. I still remember the iPod Touch keynote where they made fun of tablets and not being able to stuff them in your jeans (Sep 2009?). Then 2010. iPad launches.
In retrospect, did he need to say that in September? Maybe to fend off the onslaught of netbooks, but as stupid as his statement was, a single product in 2010 pretty much slaughtered the netbook. That combined with the increased affordability of the MacBook Air and other PC makers jumping in on ultrabooks really signaled the end for netbooks.