Ok, so what you are saying appears to support Pedal Me's position as reported in the article. They say: (a) wearing helmets encourages risky behaviour; (b) the added risk of accidents outweighs the increase in safety during an accident. You are giving an example of a community who only engage in a dangerous activity if they wear helmets, supporting (a). And I imagine you would agree that you are less safe wearing a helmet and going downhill longboarding than not wearing a helmet and not going downhill longboarding? If so, that supports (b).

It's not a conclusive argument, of course, and I have no axe to grind on this issue. It's just that I think that you might not have taken in to account what they are saying.