The managers actions put an end to the overt public racism.
No they didn't, the abuse continued.
And the manager sent a clear message to the staff - "I'm more concerned about keeping things quiet than standing up for you."
Good luck getting your serving staff to work hard for you after you allow them to be abused in public and then appease the abusers.
They also protected server from potential dishonest complaints about “bad service” and meant the server didn’t need to wait on a hostile, racist customer.
If the customer is kicked out before any service and the manager logs the time and date of the incident then that problem doesn't occur, and
no server has to wait on the hostile racist customer.
What it didn’t do is punish the racist customer.
What it did was give the customer the impression that their odious views were acceptable, and encouraged them to keep going.
This could have subjected both the server and manager to a less obvious but more harmful racism, done nothing change the customers underlying views, and disturbed the meals of other customers.
It may not change their underlying views, but it would damn sure send a message that they can't voice them in public if they want to get a meal.
What the manager did is more likely to get a better overall outcome to the situation.
The server was in tears, other customers complained and the manager got fired.
You'll have to explain how that is a better outcome.
I’m not arguing for least resistance, I’m arguing for best outcomes.
Best outcome is that the racist realises that their views are unacceptable and adjusts their behaviour in future.
Try considering your position in the context of police behavior.
Why? This isn't a police behaviour situation.
Of course, racial abuse is actually a criminal offence, so it could easily have become a police situation.
Politely asking them to leave
is the "better outcome" response to that situation.
Appeasing a customer who abuses a member of your staff is short-sighted and cowardly.