The sad fact of the matter is, had Coulter called Edwards an n-word, and gotten the same response, everyone would probably get why the situation was offensive.
Also, I'm not really clear on how anything the Democrats or liberals do or don't due is a necessary consideration in determining whether Coulter's actions were out of line. Claiming that applauding Coulter for saying faggot is okay because Louis Faracan (sic) is an anti-Semite isn't an argument, it's just changing the subject.