Harmy’s work is basically a re-mix, re-mixes are considered fair use. https://boingboing.net/2013/04/26/fair-use-decision-remixing-is.html
He didn’t just re-distribute existing copyrighted things, he took different bits of different copyrighted materials and created his own fan edit, which is very similar (but not identical) to the theatrical cuts, which can’t be right now obtained legally. He has no personal profit out of his work, and his works are used for educational purposes - they are often used to demonstrate differences done to the movies during the years, and providing commentary on them.

So yes, Harmy’s despecialized editions, just like any other fan edits COULD be considered fair use and therefore fully legal. COULD is the most important word. But why are we having such a discussion? Isn’t it safer to behave in a way in which Lucasfilm / Disney has NO reason to take any legal actions?