[Closed] All is forgiven, he can come back now....

Helmet legislation was not associated with reduced hospitalisation rates for brain, head, scalp, skull or face injuries, indicating that factors other than helmet laws have more influence on injury rates.

So it was more about whether forcing people to wear helmets reduces head injuries rather than whether the head injury rate or severity of head injuries differed between people who do and don't wear helmets. Not that this is something you can prove as nobody tends to report an accident where they didn't hurt themselves enough to need medical care.