You make a good point about Son of Sam and the Zodiac killer, but they were anonymous at the same time they were being sought by LE for crimes they committed.
It's a little different with Nancy because she was known to LE by her real name, as a witness, not a suspect. I could compare her status to the 14-year-old girl who was molested by an intruder in the case thought to bear similarities to the Ramsey case; her name was never given because she was a sex assault victim and a minor. In the case of the two teenagers kidnapped in Kern County last year, an Amber Alert went out for the girls, but after they were rescued it was revealed they had been raped by the abductor. This caused the media to question whether that should have been revealed because their names had been made public through the Amber Alert.
I don't know the grounds for action Nancy Krebs is taking or plans to take, but I doubt she is a public figure. She may be a limited public figure but again I think if she tried to preserve her anonymity as a sex abuse victim, it will be hard to prove she intended to be a public figure by going to the BPD as a witness, or by giving the two voice interviews with Mame.