you can also "fake" moisture a bit after shredding slow cooked old bird by adding bar b q sauce, seasoning as shredded chicken for tacos, etc.
Or grind and process as sausage. I do a lot of that too. If the recipe is designed for pork, it works well for old chickens.
I've butchered LOTS of birds that old and older. As the other posters said, long past tender. After two days, that's not rigor.
Recommend, as they do, long slow braise in the crock pot with just a tiny amount of liquid in the bottom. For our birds, 3 hours high, three hours low tends to be...