I'm just guessing that the reason is that FOX news is seen by many as a rather controversial news station. The ships may avoid it for that reason; I don't think I've ever seen anything but CNN on a ship. It may simply be because CNN draws more viewers/higher ratings and there may be an assumption that more passengers would rather watch it. Something to let Guest Relations know if it's important to a lot of people. It seems fairly easy to have two news channels available.