"We wanna win."
That's why.
Hum maybe American Indians don't have the same rights
The issue at hand is they don't want the pipeline run through Indian land, or across the Missouri River upstream from Indian land. They have a point.
One problem is that the oil pipeline would parallel an existing (albeit underground) natural gas pipeline, so the argument is somewhat weakened.
The other problem, and the one that destroys their argument, is they now want to dictate details and conditions of the pipeline in areas that are nowhere near Indian land, pretty much from end to end of the entire pipeline.