Sometimes these guys need to be saved from themselves - Chuck Liddell in the UFC is a perfect example.
He didn't want to walk away, but because of his age and the damage he's taken, Dana White wouldn't book him anymore - said he cared too much about him as a person. Chuck, given his desire to fight Tito Ortiz again at age 48 and being gone for almost a decade, isn't ready to give in, but if it happens it'll be under Oscar de la Hoya, and not the UFC.
This might be what the Twins need to do if the symptoms don't go away and Joe's willing to risk it.
I mean, maybe they dissipate and he's back, but is it really worth it? I haven't had a "major" concussion in 10+ years (one minor one since then, bringing the total to 6), and I still get foggy from time to time, get dizzy on occasion, and suffer from migraines. The things I did to get those weren't worth it.