Aren't they trying to confuse two issues here?
1) Apple never claimed or intended iTunes DRM-protected music to work on any other system.
2) From memory Napster was trying to spoof iPods to work with their iTunes competitor, to cash in on Apple's ecosystem. Apple just shut them down.
Interoperability was the design of the other DRM system, it failed. If all proprietary consumer systems are going to be hit by anti-trust suits I wish the law would just state this up front.