He was right to apologize.
No matter what you may think of any group, you should never use unkind epithets to describe that group.
Of course, since we are all imperfect human beings, there may be highly emotional times when an unkind epithet is unwittingly said.
For example, an Asian woman has just been murdered in the New York subway by a certain gentleman, so I can understand and forgive her family members who may be so traumatized that they let out some unkind words (either in English or another language) to describe the killer.
Some years back, I passed a man on the sidewalk who let out an unkind epithet because a minute earlier he had almost been run over by a driver of a certain background. I am pretty sure that he was remorseful for doing so by the time he got home.