Do you have any information otherwise?
If the tortoise is covered by the Endangered Species Act - a law I think ought to be repealed - then the government agency has a requirement to comply. Congress could at any time delist a species. The failure to do so is a failure of Congress and a failure of the President - which is not surprising, but there you have it. We cannot ignore laws while out of power and then expect others to obey them if we win power.
In any case, refusing to pay grazing fees on the basis that the US government controls no land is total nonsense. You might as well refuse to pay your taxes because you are a free citizen of Nevada and not the US - one will get you as far as the other.
This is all about a deadbeat rancher who paid grazing fees for 45 years and then stopped because he claims the US owns no land. He is an idiot, and he has been freeloading for years. Time to seize his cattle and sell them to pay his debts.