You really need to stop the fatuous nonsense about trashing the royal family. Particularly as Harry and Meghan were at such pains to make, in my view, a loving distinction between the institution qua institution, and the family qua family. The trashing nonsense is a tired tabloid narrative that makes the royal family sound like a mafia organisation against which insiders cannot speak without retribution, insiders cannot leave, bound in some sort of servitude with a menacing omertà. But perhaps that is how you see it.
Basically, what you mean is that Harry and Meghan are supposed to just take the abuse of the family, aided by the tabloid media, because they left, but are trashing the family if they defend themselves or explain in any way.
Unless you mean it's okay for them to be hounded as relentlessly as they were without ever defending themselves.
Why is it not "trashing" for Meghan to be accused of making Kate cry, but when Meghan and Harry explain what happens, it's trashing?
Why is it not trashing to smear Meghan with anonymous bullying complaints, announce a big investigation just before the Oprah interview, then not release the results, but when Harry talks about William assaulting him it's trashing?
Why is not trashing when press releases are issued in Harry's name without his knowledge, but when Harry points out that the press is working hand in glove with the Palace it's trashing.
Why is it trashing for them to push back against the sexist narrative of "Megxit", or for Harry to explain that it was his decision. Should they just accept that narrative, without pushing back and explaining what it was that led to their departure?
I could go on, but you get the drift.