Palin is a public figure NOW and has been since she was nominated for VP. She also doesn't have to worry about the public figure thing because she has proof the guy knew he was telling lies since he admitted such in his emails, which her lawyers have, hence the letter to RH putting a hold on any attempted destruction of correspondence between them and Mcnumbnuts. The law doesn't state public servant, it says public figure and she certainly is that. But she has RH by the short hairs and I expect they will want to settle out of court and pull the book off the shelves.
However, if the law did state public servant then she could still run since the lies were told before she started her run for President(if that happens)and laws are not retroactive.