I think he simply doesn't see any real benefits (for Apple) in open sourcing it. Surely the occasional geek will benefit, but there simply isn't that much market pressure for Apple to feel the need, neither other benefits, like it gets with the open source darwin.

The fundamental thing I think you're missing is that the assertion that open source benefits users, hacker and the company is not undisputed. Apple's stance on the matter, for example, are almost the opposite; for Apple it may benefit hackers, but it's bad for users (who may suffer unneeded complexity and confusion) and it's bad for Apple; at the least, it's a distraction and waste of resources to release an open-source version with the polish it ought to take, at the worst it may enable things Apple wouldn't want, like facilitating competitor's devices ability to fake as an iPod.

Not that I think Jobs is actively thinking about it, I'm pretty sure something like this doesn't crosses his mind. If asked maybe he would say 'go get another mp3 player then, or use Windows/Mac OS X'.

By the way I'm not saying I think Apple is right or wrong, just saying what I think are it's motives.