My guess is that the article is a propaganda piece, designed above all things to elevate Romney's status and make him look better. I don't think the author, if pressed on the point, would either commit to a prediction that Romney will receive an overwhelming amount of the female vote, nor to a normative claim that women, ethically, should vote for him(1). In other words, I guess he was just bullshiting. But bullshit can still be sexist.

(1) He probably does think that women (and men) ought ethically to vote for Romney, but on grounds unrelated to the topic of the article.