That excuse was given after the incident.
The restaurant should have told them first thing when they arrived that it would be a wait because they were short on help.
The manager will probably be out a job shortly.
The problem in the restaurant business is that you can have “no shows” who were scheduled to show up at any time—including after the group arrived.
I have also seen employees quit on the spot during lunch hour.
So—the details matter—and management may not have full control over the situation.
I’m guessing they don’t pay managers much. I’ve noticed that establishments that don’t pay much don’t have stellar management.
But that is just speculation.
I’m betting the Restaurant had no idea that 17 people were coming at them.