I'm not ItsVibes, what you said shouldn't happen but I think it's be reasonable he did it at least every time he used a slur against a minority person (for example this case) and the other person didn't know about his condition
The whole point of apologizing is first and foremost to acknowledge damage done. People who are aware of his condition might (and only might) not be as hurt, and that's why in those cases such a strong apology might not be needed.