Hi there and welcome to BYC! 
Resting the meat for a bit after processing can help with the toughness. We cool ours in an ice bath after processing and then store in the refrigerator overnight or 2 days. Once the chicken is really flexible again I'll cook it or put it in the freezer. We've butchered roosters at that age and very rarely have tough meat. If you rested the meat then I'm at a loss.

Resting the meat for a bit after processing can help with the toughness. We cool ours in an ice bath after processing and then store in the refrigerator overnight or 2 days. Once the chicken is really flexible again I'll cook it or put it in the freezer. We've butchered roosters at that age and very rarely have tough meat. If you rested the meat then I'm at a loss.
