The deal says, you stick to computers and we'll stick to music. This is a simple case. They advertise exclusive music for sale with the Apple logo. They are selling music.
What Apple Computers are not doing (when) using the Apple mark is selling software, delivery systems, or anything of the like. They are selling music. And that is in violation of the agreement.
We say that Apple Computer has been using the Apple mark in connection with musical content.
Apple Computer can go into the recorded music business in any way they want. What they cannot do is use the Apple (trade)mark to do it.
Apple Computer has been trying to take more and more away from us.