Am I the only one concerned about the lack of respect this shows to customers? Some families might have travelled a long way to get there as a special day out, there would certainly be large numbers of disappointed children, etc. Having a grievance with your boss and/or employer is one thing, but making innocent bystanders suffer as a result is something else completely.
Would you have any sympathy for management that purposefully made sure they had a "bus factor" of one and then blamed that person when they inevitably got hit by our theoretical bus?
Maybe apply the same logic the hardware resources if it helps to think of things with less of the emotion in talking about a person; The company has a single consumer grade PC running linux in the corner of a cubicle serving up the entire companies suite of applications, no load balancing or backups at all. Many devs and admins have come and gone recommending a more robust solution but management refuses to consider other options. Whose fault is it when it falls over?
The ex-employee contains some blame. But what they did was probably rational and _just_ from their point of view. As a manager you need to not stack up abuse on the employee to make this rational. And you need to have people you trust to open the park, if one missing person can shut down the park.