There's no moral authority here. The First Amendment doesn't invoke any authority, that's what the freedom of speech and of the press means, nobody can tell you with valid authority that how you're expressing yourself is wrong; if anybody could, then we wouldn't possess the inalienable right to free speech, but we do possess that inalienable right.
Why can't I just say the R word and all the -ubar words? This, I ask to the famous "some undefined person somewhere, somewhen" that you named. Their answer? Crickets. It's made up, by the people who are pointing fingers. If they didn't point fingers, this wouldn't be so R word. And ironically if they weren't so R word, they Wouldn't Point Fingers.