Damien Darhk knows about William, and thus so does Ruvé. Given that she is a political opponent of Oliver's, that's a pretty major card to be able to play if necessary. Oliver is currently winning, at least that's what the experts say after their debate, but opinion would surely change in a big way if it were revealed that he has a secret lovechild, and that even his fiancee didn't know. Oliver's trying to dig up dirt on Ruvé, so obviously she'll be trying to do so on him, and now her husband has handed her this. With mud-slinging tactics and dredging up secrets all part and parcel of these political campaigns, it'd certainly make a lot of sense for it to be used against him. Will she do that, or does Darhk have other plans for William?