Not always so straight forward when it comes to who stands to profit/benefit from a given project. The state of North Dakota earns a pretty sizable sum in royalties and taxes from oil production. It would be perfectly reasonable for the State to want to see a project like this move forward enough to help fund/support the project. Increased domestic production benefits every U.S. citizen, this suggests the federal taxpayers are also interested in seeing projects like this which may increase production and tax revenue.
Hell, let's face it...there's even a bit of national defense argument that can be made now that Uncle Joe has cut the national oil reserve in half. If we didn't learn anything from the 70s other than how quick the Arabs can cutoff the oil taps, that would be enough for me.