Which would still apply if the game were sold on a CD-ROM, but needed an internet connection to Sony's licence servers to run. The important bit is that once you bought a music CD, no-one can stop you from playing it?

Yes. Not just practically speaking, but legally, you own the disc.

True, but no additional rights to distribute replicas of the copyrighted music and composer works.

Note, if a band does a cover of a popular song, the original music composer rights also don't magically transfer because someone sang a slightly different version.

Sony may not be technically breaking any rules, if they disclosed the terms of the copyright are revocable... and not perpetual in the terms of sale.

Still a douche move to rip off kids, and burned a lot goodwill with consumers. =3