If I understand correctly, a capon is a castrated male chicken, right? Since this is the "Meat Birds" board, I imagine we're talking about a meat bird, right? What I can say is that I've been told that with most meat crosses used in production, keeping them after slaughter weight is ok for a few weeks, but their breasts continue to grow and become so large that they actually suffocate. I would imagine that it's breed dependent. (i.e.: if you have a breed that is used in a cross, like a Plymouth Rock, then you're ok, but if you have a Rock Cornish cross, then it won't survive.)
How old is your bird now?