“Edwards was running for President, Todd Palin is not.”
Like it or not, Edwards and Todd are both public figures. Sarah has always had her entire family pushed in front of the cameras, which makes them public figures.
Making them public figures, they probably can’t sue for disinformation toward them from the outside.
Disparaging Remarks- Making remarks about someone, especially if you name that person by name, in a social networking setting can get a lawsuit slammed on you faster than you can say the words "lawsuit".