You have an ethical problem that is unresolvable if you would even consider retaining the manager.
Okay you might only have a lack of intellect, but either way you both have a problem and you are a problem.
The employee wrote the note.
The employee posted the note on the Internet timestamping the fact that the manager was already an hour late.
So we have established by way of the time the note was posted on the Internet that the manager was at least an hour late. There is no he said : she said about that fact. It is established and only someone stupid or intrinsically dishonest would try to deny this.
Even at this point, the manager is trying to claim she was only running a half hour late. If so, why don’t we see her hand ripping the note off of the door, as she has been there with the employee for the past half hour.
She (and you) both have and are problems.
There is no excuse for her. You, on the other hand should have read the article and thought about it before posting something stupid which you cannot defend.
If this was your business, would you have allowed your employee to shutter it? I am a business owner and I can tell you with 100% certainty that the employee should have called the owner to complain instead of unilaterally deciding to close the store, resulting in lost revenues.
You don’t see this because you are not a business owner.
The disgruntled employee took it upon himself to CLOSE THE BUSINESS without approval. He should be fired.
The manager whom was late should also be disciplined, up to and including termination.
Apparently this is the station in question: