Marie Harf, Hanf, whatever it is also said ISIS was created by global warming, absolutely looney tunes but that doesn't mean, I'd absolutely say she shouldn't be a fox contributor. And Alan Colmes? Well, he'd actually often out-debate Hannity though, the two had a friendly relationship.
These networks are looking for recognizable faces to help float their ratings, so who knows? If they are just guest contributors, they may have? Like what? 20 minutes max a week on air? I don't follow Fox that solidly but it does seem like that is how it usually works.