I think what his message is meant to be taken in the "Free Software" sense. You know, proprietary anything is evil, all software should be free, hippies rule the new utopia and all that. I won't speak for Microsoft as I'm not sure how they do it but what you mentioned with Apple and iTunes is pretty much it right there. What people who repeat this message forget is that this "lock-in" is not bad or evil to many people. Sure, the hackers want to install their own apps and use alternative app stores and all that in which case I'd say find another (or create another) platform. My mother and the vast majority of consumers want to tap their screens a couple of times and get a cool app. It's not lock-in to them. To them it's easy and convenient. Technology is for everyone, not just those l33t enough to hack.
I find their revenue models very different, Apply making it on hardware + iTunes (Music, apps, movies, etc), MS making it on Software.
How do you group them as the same? And call it 'Lock-in'?
Edit: for clarity