He hadn't actually signed his fight in December. That's the point. He could have been negotiating this deal with Usyk instead of lining up a super fight with Chisora.Fury was already fighting in December at that point. I’d love to see your response if Fury offered someone a fight who had a fight coming up, no doubt it would be disrespectful, ridiculous etc.
Imagine Joshua was fighting on December 3rd and Fury offered him a fight in February