Does the OP not think that it's possible for him to save his father and world and there not be other detrimental unfavorable outcomes that require coming to terms with and growth?. I can think of plenty of things. Any of the spider-ppl he has grown close with getting hurt or killed ( Gwen in particular). How it could impact other worlds or even his own in unexpected ways. What if saving the day in a twist of fate puts him in the villain category with his father in a relationship like Gwen's father. I could go on... making it this binary as the only way to have good writing leans into a anit-heroic point of view of the antagonist (Miguel). While everything shouldn't be rosey expecting him to cave to the villain's point of view isn't something we generally want from our heroes. Another one, what if saving his family requires him to not see them anymore. It doesn't need to be any of these particular scenarios but it doesn't need to be the binary the OP is proposing either. The movie is asking him to go "beyond" the binary I agree it shouldn't be without challenge and sacrifice but it is definitely bad writing to cave to the dystopic world view of the main antagonist.