Hyperbole aside, I have to acknowledge the gripes you have. Yes, the GPL is a funny license when it comes down to it.
IANAL, but my understanding is that anything that Sun, and by acquisition Oracle, contributed to the MySQL code can be changed to non-free licenses for newer editions. Obviously you can't say "That release from two years ago is no longer freely available." Anything in the project that is GPL code needs to have the source freely (or at least easily) accessible. So, any community contributions (yes yes.. I know... Both of them) are still covered by the GPL if the authors chose to mark them as GPL code. If they did not state any licensing terms with their code, well then I believe it became subject to Sun's/Oracle's discretion.
To properly reply to the parent that you are criticizing, they do have a point in that if the code that has been released isn't changed, it is still GPL code. That should remain publicly available. Any changes they make from here on aren't necessarily... But depending on how they make use of the GPL code they might cause a violation of the GPL license, which could be actionable... But we'll just have to see how this progresses.
So, in the case of the community, Oracle is essentially choosing to no longer license their changes under the GPL. The only real surprise in all of this is that it took them this long to do exactly that. Of course it bothers the community because someone just took their truck from the sandbox, and let's face it, Oracle ain't exactly known for playing nice in said sandbox anyway.