There are some legal issues, and it has nothing to do with prejudice. First of all, the tribe needs license from the state government to operate a casino. And the state government has refused to give permission, because the tribe in question (Shinnecock Indian Nation) is not recognized by the state government, although it is federally recognized. The state government believe that they are faking the indigenous identity, just to get permission to operate the casino (in the state of New York, casinos are not permitted outside Indian reservations).