Because it could be something else than just a consumption device (unlike a book or a photo album), as it's technically a general purpose computer. His point makes perfect sense.
No, it's a crucial one, for a simple reason: you're not supposed to change the firmware of your car, but you change the software in your palmtop computer quite often. Car firmware is special purpose (let's ignore some high-end multimedia stuff), while your palmtop computer can and does run any program.
Nothing technically prevents you from tethering a keyboard, mouse, and big screen to your palmtop computer —just like you do with some laptops when you dock them. Heck, it would be damn useful, to centralise all your computing in the palm of your hand.
The fact that your computer fits in the palm of your hand and can hook up to a phone network is not a good reason to have its usage restricted. The only reason people got tricked into thinking this is somehow okay, is because those computers are misnamed "smartphones".
No. They're networked computers. "Phone" is a distant second by now.
Granted, doing this set us back a few years. Still, for my day to day computing (everything except 3D gaming and maybe HD movies), I would totally love to have my phone run GNU/Linux with my favourite window manager when tethered, and an Android-like touch-based shell when unplugged.
That's not to say smart phones suck. I love mine. All the disadvantages have to be weighed against the value of having a network connected computer in your pocket wherever you go. There is quite a bit of latency involved in sitting down at computer compared with pulling a smartphone out of one's pocket.