Reasonable assumptions:
This isn’t the first time that this has happened.
On previous occasions, the manager did not authorize overtime or even straight time for the additional hours as to do so would expose the manager’s failings.
The manager accepts no excuses from employees.
This business is likely to fail if the owner doesn’t come up with a new manager - soon.
I did not address the manager becuase this is an article trying to make a folk hero out of a guy who was so mad about being left to run the store an extra hour he aired his dirty laundry in a sign on the front door. Regardless of the managers failings this is a sign of a bad employee. Your assessment of the manager is likely correct but tell me, how many employees do each of you have and what would you do if one of them publicly posted a letter painting your company in a poor light?