Well, I emailed the guy and posted in his forums and so on. He responded. Mainly, it seems to be that he just doesn't like the DRM in M4P files. The other stuff is a simple matter of not searching very thoroughly. It's not so much that he thinks AAC/MPEG4 sucks, it's that he thinks Fairplay's DRM sucks and that WMA has more player support.
I pointed him to Roberto's listening tests, as well as pointed out that WMA-DRM is, if anything, far more restrictive than Fairplay, as well as pointed out that RealPlayer 10 can playback M4P's as well. In short, I think that he simply hasn't considered iTunes DRM as a "new" contender, which it really is considering that it's only made it to the big platform (Windows) recently.
Basically, he just found out about FairPlay, decided it sucks, and then praised the feature set/sound quality of WMA. AAC was dismissed immediately without much investigation into it.
I was able to get him to admit that MPEG4/AAC != iTunes/Fairplay though. Maybe he'll give it a closer look. In any case, he also says that ExtremeTech is trying to do their own blind testing, which I look forward to seeing.
Edit: I did not point out the lack of player support for WMA9 Pro, mainly because until just now I was not aware of it (I don't use WMA

). If he responds again, I'll bring it up.