you just assume it should be legitimately “Federal land” - thus, you so miss the bigger point.
The Federal govt purchased the land from Mexico, so they are legitimate owners. The people living in that territory failed to arrange to take title of the land when the Nevada state constitution was created, so it has remained federal land within the state’s boundaries since the original purchase. If Nevada really wanted it, which they apparently don’t, they would have to change their constitution, among other things.