The answer from Toyota, where this kind of thing (anyone can stop the assembly line if they think there's a problem) originally came from: if the employee reasonably believed there was a problem, they suffer no consequences (and perhaps even get a merit) for pulling the red cord. Because you lose much more money next time there's a real problem, if no-one dares to stop the machine.

If yanking the cord on a single system causes losses that are intolerable to the business, the business has serious continuity problems.

It was an employee today, but the cord was going to get yanked anyways. A data center tech who pulled the wrong cable out, a power cut, a backhoe with a taste for fiber, whatever.

So long as the employee was acting as best they could with the information they had, the resultant business implications are really the businesses' fault. Having a system that cannot be recovered is risky. Assuming that system will never die is foolish. Blaming the employee is pointless.

My vote would be to understand why the employee thought it was necessary to shut the system down, and then educate them (and the rest of the department, since it's probably a collective problem) on why it wasn't necessary and what they could have done instead or how they could have known it wasn't an issue.

That employee probably also deserves a couple days off once the system is recovered (delivered in person, by their manager). It sends a message that they're not in trouble, but more importantly, they're likely fried from trying to juggle internalizing their mistake, getting the system back up, and worrying they're going to get fired because _this_ is how the CEO learned their name. They probably shouldn't be near a prod system for a couple of days until they've come down from the adrenaline and had some time to internalize what happened.

This is just unnecessary contrarianism.

Layoff. They were costing the company money for irrelevant problems.