So my objection is that the movie inserts this loose thread (Old Joe 1), which is not really resolved. Everything else - to my understanding - is resolved. Except for this part of the storyline.
You may think you want that. But when a 5 minute sequence is in the middle of the movie explaining this "loose end" which adds nothing to the main storyline but just ties up something that maybe 2% of the audience is curious about, it will stop the movie in its tracks and you will say that the movie felt long and draggy. And so as a storyteller you have to make choices, and decide what is part of your story and what isn't.