Sexual behaviour doesn't have anything to do with the ability to govern. Thats like saying someone who can't drive shouldn't be a particle physicist.
Leadership and more importantly integrity does. These people aren't guilty of being sex fiends but rather a chronic and have a borderline psychotic inability to tell the truth.
I find it funny and telling that some public figures have no problem in dealing with questions they don't want to answer in difficult circumstances and others seem to think an obvious lie will get them off.
Recently for example, Piers Morgan on CNN asked Ann Coulter [another controversial figure] to talk about her personal life. When asked she said, "my personal life is my personal life and I intend on keeping that way." Morgan tried to rephrase the question and she replied, "....you can rephrase the question as many different ways as you'd like Piers, but I'm not going to talk about it."
Wiener instead of lying about this whole incident could have said from the outset that the whole thing was a personal matter and that he wasn't going to answer any more questions about the matter no matter how many different ways people want to pose the question. He didn't obviously - he lied and that's the problem IMHO.