Rush should not have apologized for telling the truth.
You're missing the point. He didn't apologize for telling the truth, he apologized for using a vile, inappropriate word(s. He apologized for stooping to the left's level and insulting a woman with which he had no knowledge of her activities. He apologized for lowering his standard.
Granted this is obviously a ploy by the left to smear Rush, but that's nothing new!