Comment: Excellent use of political symbolism here. I wouldn't be surprised if this event got a lot of coverage in the local media.
Of course, it's also common to use Indians as symbols of political rebellion (e.g., the Boston Tea Party). The activists could dressed as Indians and knocked over a few (fake) slot machines. But that wouldn't have worked in this case, since the activists are protesting against Indians.
For more on the subject, see Chinatown vs. Foxwoods and The Facts About Indian Gaming.