Fedor isn't ducking anyone. Fedor is loyal to M-1 Global. If the UFC wanted Fedor, all they had to do was agree to cross promote shows with M-1 Global. Strikeforce will cross promote with M-1 Global, hence Fedor went with the promotion that gave him what he wants.
Who would Fedor be ducking from the UFC? Fedor has absolutely demolished anyone from the UFC that he has faced and that includes 5 different UFC heavyweight champions.