I find this to be rather perplexing. Boorman's film was based on the "definitive" medieval Arthur tale, Morte d'Arthur and was simply adapted by the director and Rospo Boorman. It departs from the original in a few trippy and sexy ways, but it stays relatively close to the original text. It's been a long time since I've seen it, and it always has a horrible fever dream quality for me, so I may be remembering poorly. Frankly, I just remember Gabriel Byrne not bothering to take off his chainmail before sexing it up with Igraine, and that Lancelot wore nothing under his armor.
So why not just, you know, write a new adaptation of Morte d'Arthur? An insistance on obtaining Boorman's film rights suggests nothing more than a shot by shot remake which is silly. There's plenty of sex, violence, and fantasy to be wrung out of the original Arthur legends. The whole myth has been begging for someone to tackle it, and bring a Pre-Raphaelite version (only R rated!) to life instead of another dull "Here's the true story behind the Arthur legend" film. I'd criticize more harshly, but frankly I'm just perplexed by anyone who opts to remake rather than return to the source material.