I don't understand too much about how it works or how that it is different from a Gamecube memory card other than having the USB slot. Since it works by using the Gamecube memory card slots, it seems like a Gamecube memory card. I have this old tool for the Gamecube that looks closely similar. It's a Gameshark Gamesaves memory card for the Gamecube that was used to transfer Gamecube Gamesaves between Gamecube and PC if anybody remembers. Since this can also connect to the PC how is it different than the USB Gecko and cannot be used the same way?
As far as i'm aware the logic doesn't touch the EXI bus it just programs the onboard flash. The EMS one does that anyway.