Und das bestätigt auch meine Erfahrung, dass das SD nur in Direktanschluss an ein MAC funktioniert.
There appears to be some sort of handshake happening between the MacBook Air and the IDE to USB bridge within the MBA SuperDrive. I looked into re-flashing the controller (which is a standard part) with generic firmware, but after several hours I was getting nowhere.
The alternative was of course to replace the IDE to USB bridge with another one, which is exactly what I ended up doing. The trick was to find a small enough circuit board. I was about to give up on this mod when I stumbled upon the aforementioned $9 part on a series of tubes.