The Feds are in an awkward position here - they have a duty to prevent discrimination "on the grounds of race" in matters such as this, but they also have a duty to respect the hard-won jurisdictional rights of Native bands/tribes/nations. In this instance, it looks like they do not want to be seen once again marching into Indian country to enforce their will, and they do not want to be accused of breaking another treaty. They're probably hanging back till the issue wends its way through the courts ...