Nothing could have stopped them from having an F3 if they really wanted it, nothing at all.
True, but so what? It doesn't prove they were planning F2 all along.
Anything you do after a player quits could be prejudical to someone's game. When Bruce quit in S12, they didn't play the challenge planned for that episode which could have been their golden opportunity to beat Terry and boot Terry\Aras. Having Terry\Aras both immune at F4 if what cost Cirie the game.