At least by keeping 'his head down' PA is mitigating any further embarrassment to the Royal Family, whereas H & M seem to be doing the opposite.
An interview with Oprah is what many aspire too. Often regarded as the one that brings the maximum publicity; as high as they can go, or as low depending on your point of view.
Regardless of what the interview reveals, perhaps the Royal family will have a collective sight of relief once it's been aired and the ensuing publicity dies down.
Anything else they have to say surely will be 'old news' as it's all been spoken about, and hopefully any future disclosures will be infrequent and less publicised.