I think it's blindingly obvious that no, they don't take advice. And if someone gives them advice they don't like or don't want to hear they bully them then they fire them.
They've hired plenty of shrewd, experienced people and then ignored them, what was the point of that? It's such extreme hubris - quite extraordinary and fascinating to watch (hence we're on thread twelfty three or whatever it is).
I think they are also forgetting that their young compliant children will grow up - we're only 6 years from Archie being a teenager - and they're going to question what they've been told.
Later, surely they're highly likely to say "hang on, explain it to us again? Why aren't we in touch with any of our family? What do you mean, our grandfather was the King of England and we weren't allowed to meet him? And now your brother is the King and won't speak to you? What about our other grandfather? What did he do that was so terrible?"
And they will, at some point, go online see the facts for themselves, read Spare, see the OW interview and, I would imagine, be horrified.
Karma will bite them on the ass (American pronunciation fits well here I think!) and their kids will quite possibly be furious at their toxic upbringing and the opportunities and riches they've been denied.
And you never know, they may decide to stop all contact with their parents, because they've been shown that's what you do and that's what their role models did and there you go, what goes around comes around.