That is the exact reason, why GC USB loading doesn't work, that crediar posted at the DM project page a couple of days before he took it down:
QUOTE said:Why GC USB Loading won't work
The Wii has two main memory regions MEM1(24MB) and MEM2(64MB) the GC had MEM1(24MB) and ARAM(I think 16MB I can't find the value right now).
Now as we know some facts we see that the Wii has no ARAM, but GC needs it to work!
So when switching to GC mode a part of MEM2 is used as ARAM(the infamous twiizer attack was possible due this fact).
So why is this a problem? once it's turned into ARAM it's not accessible from ARM( aka starlet, aka IOS) anymore, why is that bad? well the EHCI(aka USB2.0) device can only access MEM2 so no MEM2 no EHCI and no USB.