Not quite. The Pinal County Sheriff's Dept. covers the Village of ChuiChu.
But you are correct that the T O is wide open. Small police dept. and and a lot of territory. It is the second largest reservation in Arizona. Plus, it extends INTO Mexico.
Border Patrol is pretty active there, but like everything there are too few with limited resources.
When I lived there TO would not allow anyone to patrol their Sovereign Nation.
No BP, No Sheriffs, No Nobody.