the disagreement is that he COULD come back if he chose to
whether he SHOULD come back is where we agree
Yes, I agree that he shouldn't.
I'm not saying that he couldn't, but that he will not.
He could come back, but he wouldn't be close to the same. He relies on that leg for power kicks, as well as power punching, and moving in and out. That's definitely going to mess with him mentally, and he'll never be confident throwing that kick again, and probably hesitant with his other leg as well.
He is out for 6 months regardless, but if he chooses to get the metal rod out that's been inserted, that's another 6 months, so he won't be able to train till 2015. If he doesn't have the rod removed, the bone around the rod will be even more susceptible to break.
After he has a year off (provided that everything goes according to plan and he doesn't re-injure himself), he'll be out of shape etc., and I just don't see him coming back. That was career ending injury, in my opinion, given his age and the accomplishments he's already attained. As you said, he doesn't really have anything to prove. Add this surgery to his multiple shoulder and elbow surgeries, and he probably feels older than 38 already.