I think there are two reasons for the prostate thing.
Firstly, the campaign to normalise prostate issues and treatment is a big thing, has been for a few years. The football people on Sky always wear the badges, its to help dispell the myths and shame around the whole thing. The fact that the King has said he has these issues and is being checked, despite being in his 70's and part of the buttoned up establishment, is a good thing. It helps with the "it can happen to anyone" message.
Secondly, yes I do think that the information has been released now (if it was ever going to be released at all) because of The PoW's illness to try and deflect from it. And why not? Who hasnt tactfully taken one for the team in order to protect a friend or relative from nosy questioning. My sister did it for me when I was going through a miscarriage. I did it for her when she had very recently been told that there was no way she could have kids. Its what you do.