i------------> first its a matter of course that Madara isn't finsihed yet and he is gonna troll kaguya and make his badasss return !!!....
-the crazy plotwist that might happen when madara makes his return is that...he is gonna get mad at kaguya and black zetsu for trying to finish him and defy kaguya in fight....and it will be the most badass fight in naruto manga
-cuz Madara is a warrior by nature and likes to fight strong ninjas..also madara is always proud of himself being "Madara"..he will definitly not accept being used by a lady...also madara's anger at kaguya might be so great to the point madara wont care about finishing his Moon eye plan but instead he will have a new goal wich is to finish off kaguya...cuz remember Madara always blamed kaguya for starting the cycle of hatred...also madara has an ultimate goal to deprive the world from the evil chakra...so what madara meant by evil chakra could be kaguya who ate the holly fruit......
-kaguya may have the strongest chakra...but she isn't skilled in ninjutsu...cuz jutsu was created by hagoromo...so if madara had considerable knowledge about hagoromo's thechniques , then he can defeat kaguya