There is no more reason to believe this story than the "collusion" story. If MSM can't use unnamed sources with along with no other proof, then we can't excuse fox for doing it with this story. That doesn't mean that it didn't happen, just like it doesn't mean Trump didn't collude. It's just that there's no reason to report it that way until they have some reasonable proof to show, either for Seth Rich's murder or Russian collusion.