Alameda Slim and his nephews took over a place called Echo Mine. Of course a place called "Echo Mine" would be Slim's hiding place of choice. He loves the sound of his own voice.
We last see the Willie Brothers, Mr. Wesley and Rico get their butts kicked by the animals and locked in the train car. Assuming they're never found by the authorities, are those five villains gonna starve to death in that boxcar?
If Grace hadn't been Immune to Mind Control, all three cows would be utterly helpless against Slim and his singing.
