While I would agree that the firefighter's comment was racist, stupid, ridiculous, etc, the comments were Constitutionally protected. Somehow we have forgotten that extremely important point.

If he refused to rescue a person from a fire, or refused to participate in doing his job and putting out a house fire because of the person's race, he should be fired immediately, but he should not be facing any repercussions from his expression of his personal beliefs.

Freedom of Speech is exactly that. Suspending him is unconstitutional and a much more serious, even treasonous act.