I think you are missing the big part about Linux users like myself not caring if Linux blows into the mainstream. I frankly don't care, I enjoy using Linux and I support all those who are interested. But if you don't want to use it, I view that as your loss, nothing more.
At any rate, if iTunes was ported over I for one would not use it. I already have iPod support, and combined with Amarok, (which I believe blows away iTunes) I have no need to deal with proprietary software.
When Will Apple Notice Linux?