It’s always worth noting that this kind of book is often based off second or third hand information (although Tina Brown isn’t exactly some downmarket tabloid hack).
That aside, what are the big revelations here? William apparently likes spending time with the Middletons because they have a traditional and seemingly happy family set-up… it doesn’t take a genius to see that might be true given that he grew up with the world watching his parents’ marriage fall apart and commentating on every aspect. It hardly suggests some nefarious influence.
Harry couldn’t see the appeal and wanted a different lifestyle. And? That’s hardly unusual. I didn’t see anything where he’s supposed to have said he can’t stand the Middletons or thinks they’re awful people. It just isn’t his world. It’s no different to my sister being a happily married devoted mother and me not wanting a husband or children.
This really is a non-story, whether you’re Team William, Team Harry or don’t give a toss either way.