I think the two scenarios are similar, but in the first case, the employee's ability to leave was de-facto -- of course she can leave any time she wants. That's part of the risk the employer takes. But if you want to balance that equation the other direction, that needs to be just as explicit up front. The possibility of a company 'exploding' is precisely the possibility the employee is hoping for. If you want to put a cap on that, fine, just make that cap explicit up front.