Actually, the user interface should reflect that somehow.
So... either we should gray out the menus that depend on audio overrides, or just override the audio always. On the other cameras, audio overrides are always enabled (but that's a technical limitation).
I don't know if the 600D audio implementation is robust enough so it can stay always enabled. That's something you - the testers - should tell. If it is, I'd prefer to implement it because of reduced UI complexity.