Except those unfinished works did have the right sold. As earlier as 1976 the Saul Zaentz Company (who got the rights from UA and/or Estate) had limited matching rights to the any film adaptation of those unfinished works. It was either as the original deal or as a deal Christopher made. If it was Christopher those rights would have been made a year prior to the Similarillion being published.
The argument you are making though is silly because it means that Canon is only what Tolkien published in his books. Yet almost all fans accept his unpublished work as "official". Which means you are creating a standard that most people don't follow. It is also silly to say them being unfinished is irrelevant when your entire argument is that they can be excluded from "Tolkien being okay with adaptations" because of them being unfinished.
Again the Loophole had to do with a TV series and a few other things that were not explicitly covered by existing rights deals. Notice how the Similarillion is not one of those things Amazon has the rights to and is not part of the "loophole". Of course this has everything to do with you not liking Rings of Power or the way it uses Tolkien's world. If you didn't have a problem you wouldn't be arguing so hard about how it goes the wishes of the original creator.
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So I use Tolkien's words to prove you wrong but somehow I'm ignoring everything Tolkien says? Lmao. Pure projection. The Elves do not fit your view of them yet you choose to go with your head canon over that of the author. I have never denied that Rings of Power changes his works. Some things however change little or nothing at all when you actually get into depths of his work. Stop inventing arguments simply because you weren't correct about one aspect of Tolkien's world.