Cohen was injured. AFAIK, she withdrew from the GP because she followed the instructions of her doctor who told her, among other stuff, not to do triple jumps for a certain amount of time. I think we can all agree that triple jumps are required in elite competition...
If she does like Plushenko (claiming he can't fly or do very demanding programs, but still flies the same for shows and lands quads in other events) and is doing hard programs in these promotional events, then I would think the ISU wouldn't be very happy. But so far, I haven't read anything that showed that she had been going against her doctors' instructions.