Well, actually there was some language indicated that features were subject to change. And, the technical reasoning behind it appears to be fairly sound. It seems that Apple ran into a hurdle, realized it could do more harm than good, and removed a possible feature.
Well this is like arguing about the meaning of 'is'. I used to let Apple slide on various bone headed things they did, but they are doing so many things now to screw loyal customers it makes me wonder if they are doing them on purpose. Many people bought AEBS with the explicit purpose of using it as a wireless backup device. I almost did, but luckily held off mainly because I was too busy to do all the research needed. The reason AEBS can't be used a TM device is because the airdisk is fundamentally broken at the moment. I'm sure if Apple were to just fix the Airdisk so it would actually work (try copying a large file to one if you have it and see if it completes w/o the file being corrupted) then the TM issues would mysteriously go away.