I always thought truth was a valid defense.
Senator D'Amato referred to a Jewish person. Putzhead is a Yiddish slur, meaning dickhead. When confronted about it, Senator D'Amato denied having said it. To his chagrin, it was caught on tape.
Again, it is distinctly a Yiddish slur. Perhaps you can justify the use of ethnic or racial slurs on the basis that truth is a valid defense. Using your "truth is a valid defense" argument, what other ethnic or racial slurs do you approve of?