The Rose Hanbury articles are just the press punishing William for daring to not roll over and let the press intrude. If you notice, they often surface when he's doing things in a new way that keeps press intrusion at arms length.
The press want the inside scoop. They want to know what medical condition a royal has, and have the power and threat over said royal that they can allude or leak it at any point they choose. So, for example they probably do know exactly what type of cancer Chuck has, knew what HMTLQ had at the end, also Philip. They also know far more about surrogates. The normal has always been that they knew it all. The power they have is knowing and holding it over their heads.
William and Catherine don't play ball. Flipping the script. They don't disclose and the press don't get the chance to wink and go "gotcha, we'll say nowt... for now" and then publish a slew of articles a few months down the line on a random medical condition as retaliation for them not letting the press into their private lives. So Charles probably has disclosed his cancer in exchange for favourable Camilla coverage for example.
But media has changed. Famous people don't need the hacks anymore to promote their causes or squash their misdeeds. William and Catherine have just demonstrated that an Instagram post from them can break the Internet. And the press are fucking furious.
So this kill notice, the Rose articles are all attacks to try and get William and Catherine back to the good old days where the press had the power, because the older ones who played the game are dying off. Charles is the last of them.
The press are furious that they are as clueless as the masses about kates illness. They are furious that money shots of her looking ill coming out of the hospital didn't happen. They are flexing but failing to see that people are remembering another POW who was unwell, hounded, duped and tricked by the press and ultimately died trying to manage the press intrusion in her life. And few of us are comfortable with that.