If by law they were not required to wear a helmet, and they were not breaking any laws, then it doesn't matter if they had a helmet on or not. The other driver is responsible for their injuries/death should it occur. Saying that they would have less injury's if they had a helmet on is about the same as saying they wouldn't have been injured if they were in a car. Bottom line, be safe out there brothers.. I hope to ride with you all..