Interesting. So why didn't they use a TMP? Cost savings? International distribution constraints? (I see TPMs are illegal in China -http://en.wikipedia.org/wiki/Trusted_Platform_Module.) It is somewhat peculiar given Apple's known DRM policies.
You'll find a quite different story when Palm made the Pre compatible with iTunes through reverse engineering. The certainly didn't want non-Apple devices in the iTunes ecosystem and spent quite some effort to put a stop to that, even though it had nothing to do with DRM.