Just a guess, but I bet it is because they know it is not valid and do not want to get sued silly. Just a guess.IDK, I don't make those decisions, nor do I frequent those news outlets to see why. To me, this would be worthy of a Special investigator with subpoena powers to determine if Quid Pro Joe broke the law, but I'm just an ordinary citizen.
Why don't you email the networks and find out?