I find it completely bizarre that we're debating this at such length.
Step back and realize that we're talking about playing a dangerous, physical game for money and fun.
Yes, if you have had a concussion, doctors can and should and probably do advise you not to play again. But if you're a grown man who is well-informed and understands the risks you can take that advice however you want.
In fact, if you are the healthiest person on the planet, and you ask a medical professional "should I play a game that involves ice skating at the highest human speeds possible, throwing myself into other people, and swinging wooden sticks as hard as we can to make a chunk of hard rubber fly at 100mph at eye level?"
Frankly anyone should advise against that. It's just a stupid, stupid idea. Just like jumping out of a plane for no reason is a stupid idea. Skiing is a stupid idea. Cliff diving is a stupid idea. Skateboarding is a stupid idea.
Medically, in terms of risk, if you are concerned about your long-term health and well-being, everybody should be advised against all of these things. There is no good reason to do any of them.
But we're all grown adults who can assess our own risks and make our own stupid decisions, and we want to have fun, so we say **** it.
If Franzen was well-informed about the risks, and he still said **** it, I say power to the Mule.
Yes, it will be sad if he ruins his life, but beyond that there is nothing to debate, and it should not change the fact that everyone should be allowed to make their own decisions.