That may be partly because the OP was written by a person who doesn't really know what he's talking about. (No offence intended, but it's true). He's little more than a parrot, repeating what he has been told and has heard from others. He doesn't truly understand what's actually going on.That really wasn't made clear in the OP. The way I had interpreted it was that they were using the save exploit to communicate with the board and have it act as the storage device, but I guess having the overflow read from the SD card is a good step in the direction of homebrew.
Anyway, I just wanted to make it crystal clear that that extra hardware is NOT essential for running code via the exploit that neimod & yellows8 have created, it is just useful for them for developing the exploit and probing the 3DS further to map stuff out for creating a homebrew SDK etc.