That is mostly incorrect. The US government has owned the land at the end of the US Mexico war via the treaty of Guadalupe Hidalgo.
Now does the tortoise have something to do with the US governments unwillingness to continue to lease out the grazing rights ... likely.
Thank-you!
My understanding is that the grazing lease was sold to a conservation group who then retired it from grazing and that they sued the BLM to have the cattle removed from their leased allotment. Bundy screwed himself when he refused to sign the 1993 lease. Now maybe he was inspired by the Hage case that was going on at the time, but the Hages always paid their fees. The Hages won in court, Bundy lost.