Warren basically says that Fury vs Usyk signed a two fight deal. And neither guy is able to fight anyone else apart from each other, in their next two consecutive fights. So they're literally stuck with each other legally.
Sounds like this means Usyk agreed to a deal where Fury could delay their fight for some time, and Usyk can't legally fight anyone else in the meantime.
Historically, it's a meaningless fight between two dethroned champions who both lost their last fights but were awarded wins due to gift treatment from corrupt fight officials. So it's for a fake "undisputed" accolade between two fake champs. I see it as a fight between two top 10 guys now, not 2 real champs. Still a real interesting match up I'd like to watch. They just shouldn't offend everyone's intelligence by calling it "Undisputed" because both guys got beat.
@14:30
https://www.youtube.com/watch?v=T_0yQZXJ8sA