Any bike going over 70 mph is a problem, not because they can't go that fast but because they shouldn't. Most people do not have the reflexes or muscles to control a 600lb plus machine in an emergency situation. I know all about that because of friends of mine who are now doing 1 mph in the wheelchairs that are the sole means of transportation they can depend on now. And I have been riding bikes for over 35 years, And believe me Helmets do not Help!
If you are using muscles to control a bike, you are doing something wrong to begin with. Countersteering requires very little physical exersion even at triple digit speeds. As for reflexes, that is up to the individual. People should know thier limitations. This applies just as much to people in cages.
And believe me Helmets do not Help
Strange. A helmet helped me from getting my head cracked in two on one of my spills. Same for my friends who have gone down.