It's more of a bribe. Train your replacement and you'll get severance and a good recommendation and can collect unemployment. Don't and you are fired for insubordination and can't even collect on the UI you've paid into all those years. But you are correct, nobody can FORCE you to choose the former over the latter. A private person doing this to another would be charged with extortion, but what the hey.
I wonder if extortion could be charged nevertheless? At the very least the given company would be squirming mightily at the media coverage of how it tried to screw its employees(even if the plaintiff was found not to have a case)!
It is extortion....you are losing your job but if train this person, we’ll given you some severance, don’t train this person and you’ll be fired with a bad reference! I’d like to see it tested!