Something tells me that Time Machine will not work via Airdisk until buggy firmware for aeBS (yes emphasis on BS) is fixed. The airdisk has never worked perfectly for me, on any of the firmware revisions.
You're probably right. That box has been more trouble than it's worth. I've had Linksys routers that were more stable and reliable. The Leopard firmware update was a nightmare.
Still, I need that Air Disk to work.