That kind of language and treatment of staff should result in ejection from the premises and a permanent ban, do not pass go, do not collect $200. Not indulgence!
Wasn't trying to get fired, frankly. I made up to $40/hr there at 20 yo. My boss was black, too. It was in the South, so it was more of a bad fact of life and treated as such by management. I agree with you, though. Nowadays, I wouldn't hesitate to refuse service.
I didn't mean to suggest that you, personally, should have refused them. But perhaps your boss should have. When was this? I didn't think naked racism was tolerated in public even in the South in past few decades. Perhaps I'm naive.