According to the GSS, here is the distribution of religious affiliations for American Indians (sample size = 1,818--I didn't count the white wannabes)
Native American 4.1
Wow! A whopping 4 percent of American Indians belong to an indigenous faith.
According to the most recent GSS Survey (2008), 0.7% of Americans are Amerindians. So the Tucson event catered to--what--about three people? I've got more cousins. Organizers didn't give a damn about the wishes of real, live Indians (or they would have asked a Protestant minister to pray). They really care about their fashionable liberal buddies.