Private party, private house people can be as racist as they wish in their own home. The fire-fighter would need to show that his boss, using his work situation, pressured him into going and that the boss knew there would be these things on display. But given the state of courts and government today this guy is probably a shoe-in for a pay day.
The dentist who threw the party has already had to resign and every politician and business has already found the guy guilty. Guilty of throwing a party in July.