It is the case. Nevada cannot grant grazing access to public land that it doesn't own. The U.S. owns that land and has since 1848, which was 16 years before Nevada became a state. Nevada disclaimed all right and title to that land when it became a state.
There is a valid argument to be made that Nevada's disclaim was unconstitutional, but that is a separate discussion. Under the supreme law of the land right now, Nevada doesn't own the land.
The original agreement between Nevada (or any state) and the federal government bestows certain rights the state retains.
The federal government cannot ‘own’ land in a territory that is not a state. It can ‘administer’ and claim legal or territorial jurisdiction over a territory; but never ownership. When a state is incorporated the land jurisdiction is made a negotiated part of the agreement between the state and the federal government.
Your argument that the federal government ‘owned’ land in Nevada falls flat. The land was never bought from anyone and there was never any title to it.
The ranchers grazing on that land for generations were never encroaching on it. The federal land grabs came later and many of the grabs were driven by special interests.
We will see if the governor of Nevada decides to assert state rights and if he doesn’t, we will see what Congress does about it when the Nevada caucus gets revved up.