Firstly, Gracie was not, at the height of her earning power, a child. She was I believe 18 when she was named a Covergirl 'face' and 19 at Sochi which is when her star really was hit its zenith. While that is young she was still an adult and any such rules set in place would not have affected her. Certainly she earned some prizemoney etc as a junior, but as has been discussed many times, prizemoney is not that much compared to sponsorship and endorsements in this sport. (Someone who has read the book, please chime in if I have got it wrong and she did earn heaps as a minor.)
Secondly, while I totally agree that rules should always be put in place for children, said rules also have to also be written very carefully to protect their right to privacy above prurient public 'interest'. This is why good criminal laws are written to shield a minor's identity and sometimes the details of the matter from the public record.