Honestly, I don't have a problem with this. Indeed, it's a lie, but it is not a dirty, filthy, corrupt lie. Consider: Sarah Palin was the sitting executive of a state. Most of us down here may not have heard of her, but in Alaska, she's a household name, and very visible in the press. Thus, her children are all nominally known. If her teenage daughter gives birth, it's going to be a minor public spectacle. Rightly or wrongly, her name's going to be in the paper, her parents' values are going to be called into question, and probably some asshole is going to take some shots at her. Who the hell would willfully expose their daughter to that?
If claiming her daughter's child is her own relieves her daughter of public embarassment, that's fine. I don't even think it disqualifies her from office.
(Really, I don't need anything more than "used her elected office to carry out a personal vendetta", even if the target is an asshole.)