It's why you never see ordinary citizens being quoted in ways that might embarrass them - in newspapers or the press. Even police quotes - from those below the 'officer' level will (if they might make the police officer look bad) not be covered...
Same with government officials - the young office clerk with no knowledge of how the press works - will NOT be quoted because the paper can be sued. Her life and comments won't be covered in a book either - not if they make her look bad. Below a certain level you're allowed some privacy... put yourself up as a public person and that's gone...
Above that level and it's 'gotcha' and 'fair game'... Sarah's held herself out to the public - - that decreases her chances of winning - and a case would open her life up to things we really don't need to know about her... Court cases are usually part of the public record...
That excerpt I posted explains the differences.
If she sued she would be interrogated under oath over her entire personal life with everyone in the world watching and it's very unlikely that she wants to go through that.