slight nitpick: it wasn’t Hustler v. Falwell that set the public figure precedent; it was New York Times v. Sullivan (1964) initially, and later Gertz v. Welch (1974?) that drew the distinction between public and private figures. Hustler v. Falwell was primarily an emotional distress case (Falwell’s problem was the use of his mother in the Hustler ad) that was decided as if it were a libel case.
Which is significant. Even if Edwards avoided saying South Park libeled him, and wanted to say it caused emotional distress, thanks to Falwell we know he’d be held to the same test as if he were suing for libel. Meaning, he’s a public figure, so tough luck.