Old chicken hold up better and doesn't dry out like young chicken in soups and stews. Yes, they become tender in a pressure or slow cooker and the meat falls off of the bone.I'm looking at possibly having to cull a 8-12 month production red/RIR red mix cockerel/rooster, so I'm in a similar position. Would pressure cooking (canning) make the meat tender enough to eat? I'd use it for shredded chicken tacos.