I agree completely with your interpretation of the GPL. However, from my limited understanding, it seems that the situation in question was indeed about a "version A". I'm not suggesting the author can't release a future version under another license, or none at all. Of course he can.

I'm saying, if he releases version A under the GPL, he has to comply with the terms of the GPL for that release.

In any case, I'm no fan of the GPL, so it's no sweat off my back. But I don't understand someone releasing a software version under a certain license and then getting upset because someone asks him/her to abide by the terms of that license.