Steve Jobs was famous for changing his mind at the drop of a hat. This is nothing new. If it is a viable product, and Apple can do it better than anyone else, then Apple will. If Apple was against something previously that they now make, it was because at the time they were against it the product was not viable, or Apple couldn't make it better than anyone else. You can already hook up a bluetooth keyboard to an iPad, which is makes it more like a laptop. You could keep debating it for a few more pages of the thread, that would be wonderful.
The reason a bigger iPhone makes sense now is for completely different reasons than for why Apple was originally against it. As people age 40+ their eyesight continues to deteriorate (both nearsight and farsight), and there are many people with weak fine motor skills. In at least BRIC countries some people only own a phone and no other computing device, which was unheard of just a few years ago. Anyone with aging eyesight or shaky hands, without a desktop, without a laptop, without a tablet, will appreciate a touch-screen based phone with a larger screen. Steve Jobs was also vehemently against an iPad with a smaller screen, yet Apple still released iPad Mini.
If a person of high rank at Apple said it isn't currently viable to sell a Mac with a touch screen, I expect that to hold for some length of time instead of being only empty words.