Being a Police Officer
The main issue was the fact that the restaurant was only concerned about what happened when they realized that a police officer had been mistreated. Without his uniform, Karl was treated horribly and without any respect.
What Would Have Happened?
It begs the question: what would have happened if a regular citizen had faced this kind of discrimination? Would the situation have been rectified in the same way? If he was a non-police officer and just a regular black man, would he have faced a similar situation?