Bundy and his ancestors had surface rights to the land since 1877. His ancestors established these rights when they settled the land. These rights are recognized by state and federal law, and the Feds tried to buy his surface rights about 10 years ago. Even if Federal gov owns the land, that does not mean that they can confiscate or displace the previously established surface rights.
If someone owns a piece of land with an oil well on it, and the oil rights are owned by someone else, that person cannot sell the land and include the oil rights. So if the Feds took ownership of the land, they cannot by fiat, take the surface right w/o compensation as indicated in the 5th amendment.
I don’t see why this is so controversial that even so-called conservatives are having trouble with it. I guess they cannot envision a time when the land was open for the taking to settlers.
The courts don’t seem to agree with you.