With all due respect to Walker, I don't see any way for this to end well.
If he wins, he might decide to fight more. Dangerous for his health.
If he loses, it could be dangerous for his health. He could really get hurt out there. Would his pride allow him to tap out?
How many of us have seen a boxer fight when he was past his prime? It's not even sport at that point. It's a pitiful, eyes-averting, shameful mess. I want to remember Herschel for his exploits in the gridiron, not for his mistake in entering the octagon.
Ex-football players need to realize that there's a reason why they're still not in the league.
Those advisors, sought out or not, who encourage you to be wise, hang up the cleats, sneakers, or bat and glove, are not disrespecting you, but rather doing you a favor. They are in fact giving you the ultimate compliment by urging you to see your own value, apart from what you can do athletically.
There's a way to gracefully leave the world of athletic competition. It's painful, but you find a way to do it. You give back to kids, do charity work, coach, become a commentator, choose a new line of work-- or even better, really focus in on life. Herschel Walker is uniquely positioned to show other athletes this path, this exit strategy, partly because he is still in shape and because he does have a measure of success outside of sports.
We each have our own lives to live. It's his decision to make. But if he asked me my opinion, I'd say,
"You're 47, you've got nothing to prove, and, No, I'm not going to fight you."