None of us knows enough about what happened to know if the owner was or was not negligent.
Suppose it was the crew's first time on a sailboat, he was asked aboard to serve as movable ballast as a favor to the BO and he received no instruction about what to wear, where to step and when to duck? Shouldn't a reasonable boat owner be under an obligation to instruct a newbie?
Suppose as a BO you had a friend or family member who was reduced to a vegetative state after a serious boat accident. Would you want him or her to have no recourse if there were things you reasonably could have done to prevent his or her injury?
Owners do carry insurance, including umbrella policies, for exactly this reason. Think of it as another item of equipment. It has a cost and if it is used and needs to be replaced it may be more expensive next time.