As long as the fan fiction and fan art aren't made for profit, I don't see a problem with it. Moulinsart are far to much like dictators.
I feel like a broken record here, but Moulinsart are legally obliged
to do what they do: they are contracted
to protect the copyright - it’s what they are there for.
For all intents and purposes they are like security guards or policemen; if you paid a security guard to stop people bopping you on the nose, and the security guard let someone bop you on the nose, you wouldn’t expect them to go “Well, they didn’t do it for profit, you see, so I thought to myself ‘Why not?’, and I stood back, like, and they bopped you on the nose…”, would you? If they let two or three people do it, then the flood-gates would open, and pretty soon you’d have a black eye and a cauliflower ear, and nobody would know whether people were bopping you for profit or pleasure.
Herge wouldn't have been happy with some of the merchandising Moulinsart do.
There is absolutely no basis for you to make that statement on, I’m afraid, it’s pure speculation. I’d say that Mme Hergée bis is a far better judge of that than you, and if she believes she is respecting his wishes, it isn’t for us to say otherwise.