Did the BLM cancel the Bundy grazing rights lease under false pretenses, namely that they were protecting a tortoise that was never endangered, and was, in fact, doing better under the grazing program than under the federal do nothing program?
Why the BLM canceled (actually they didn’t renew the lease) the lease is immaterial. They are the owner’s agent for that land. They have the fully vested legal authority of the land owner to act to represent the interests of the government and not renew the lease, period.
This is no different than if you decide to lease something, land, car, house and at the end of the lease, decide to change the terms of the lease. That is your right as the owner of the property in question.