The person watching your news will not know the fact that you choose not to share. And, while a few people may call their friends with the information, the explosive fact becomes common knowledge through news media repeating the story, not via telephone lines. Even widespread publication in one place doesn't change the harm that can come about by publishing it elsewhere. A gay hero's sexual orientation may not be a problem if reported in the California community in which he lives. The same fact published in Detroit, where his parents live, might destroy his life.
Every additional publication causes additional harm.
But sometimes refraining from publishing material results in more harm than not. Harm to the news organization. Take embargoed material, for example. This is different from the private fact situation. Here, whatever harm comes about through early release happens with the first exposure.