I think it is at least more complicated than you are painting it. If it's something that is widely known in media circles as well as political ones (at least one Democratic senator alluded to it on one of the many occasions Hillary's e-mails were brought up), the media holding it back from the public isn't really a fantastic look either.

Sometimes it feels like the media is damned if it does, and damned if it doesn't. Report unsubstantiated rumour? You're biased! Hold back information because it isn't verified? You're biased!