Probably a simple shakedown.
There's already an observatory on Kitt Peak. The original lease on the land for it was signed in 1958, and pays the tribe a crummy $2,500 a year for 2,400 acres of land. They're just looking for a new deal, and I can't say I blame them.
Odds are you could probably fit every tribe member who actually believes the gods live on this mountain in my car.