One of these things is not like the others...

[Lalwendë]

Well Christopher was certainly approved of by Tolkien to add to his work. In his will he stated:

’Upon Trust to allow my son Christopher full access to the same* in order that he may act as my Literary Executor with full power to publish edit alter rewrite or complete any work of mine which may be unpublished at my death or to destroy the whole or any part or parts of any such unpublished works as he in his absolute discretion may think fit and subject thereto’

*unpublished works

So Tolkien gave the legal right to his son to do exactly as he wished with his father's work, which shows enormous trust and faith in Christopher! Given what Tolkien stated, we can take what Christopher has added as valid. He could have done a lot of things that could be called exploitative, had he been so minded, but he has dedicated his own life to the work of his father's life.

I think as well that we could extend that feeling of 'trust' to those who Christopher approves as authorised scholars and writers.

It's a minefield out there really, trying to find what's reliable and authoritative and what's a lot of rubbish, but some, like Christopher, Scull and Hammond, Shippey and Flieger only add to our understanding, and in many cases, help us to make sense of it all.