“Can the Feds or BLM go into any of the Louisiana purchased lands and claim it protected and off limits?”
If the land has never been claimed by the state or by private owners, then yes, it remains federal land.
“Nevada became a state after the Treaty of Guadalupe Hildalgo so your reasoning is preposterous.”
As part of becoming a state, Nevada was required to agree to:
“In obedience to the requirements of an act of the Congress of the United States, approved March twenty-first, A.D. eighteen hundred and sixty-four, to enable the people of Nevada to form a constitution and state government, this convention, elected and convened in obedience to said enabling act, do ordain as follows, and this ordinance shall be irrevocable, without the consent of the United States and the people of the State of Nevada:
...Third. That the people inhabiting said territory do agree and declare, that they forever disclaim all right and title to the unappropriated public lands lying within said territory, and that the same shall be and remain at the sole and entire disposition of the United States;”
That doesn’t leave much room for claiming the land belongs to the state of Nevada.
...Third. That the people inhabiting said territory do agree and declare, that they forever disclaim all right and title to
the unappropriated public lands
lying within said territory, and that the same shall be and remain at the sole and entire disposition of the United States;”
This is clearly a complicated situation, at least in its history.