The elite COP does not require more than a full twist, though- the double salto requirement there is a D, but the twist only a B (and the full can be part of a full in, which does not test twisting particularly well).

I think the FX champion ought to show both, but in certain very specific cases, ability to show extraordinary levels of difficulty with good execution in either double somersaults or twisting can outweigh this particular compositional defect.

I also think that people wouldn't have minded McCool winning without a double salto so much if she had performed one at some other point in her NCAA career. Often, we end up evaluating routines based on what we know the gymnast is capable or incapable of, rather than what she actually performed.