Even if she would have been the cure, I would have not let her be killed. She would have died to bring a cure for who? For the assholes killing people for fun on the streets? Or for the sadistic sick dude who had some sort of romantic attachment with Ellie who was like 13 at the time? Or for the fireflies who just…

It makes sense as I don’t see how Joel who loves Ellie as his daughter would let her fight a house full of enemies without helping her, only to walk in later like nothing was happening.