A number of years ago, people were being sued after their good faith efforts to assist accident victims, with the result that people were afraid to provide such assistance. Governments responded by enacting good Samaritan laws to protect such people. I think something will need to be done along those lines to protect people who are accompanying others in high risk activities. Unfortunately, the trend seems to be going in the opposite direction.
The public expects a good Samaritan to screw up, but since some help is better than no help, they need to be protected. This is a somewhat different story. This is the story of a professional dive leader, and no, he wasn't leading, but someone somewhere expected him to act in the capacity of a professional.
With hindsight, I would never have become an instructor had I known that the world was changing to this. What happens in the case of someone who wants to take an EMT-B course to be the medic on a expedition to find shipwrecks in northern Canada, or the MPIC on a commercial vessel. Many commercial vessels must have a Medical Person in Charge, which is almost an EMT-B. What if that person is walking through the mall and sees a heart attack victim?
Does this person who is a professional aid-renderer have any duty to render aid?
Does the public have any expectation that the professional should render aid?
Does the public have any expectation that the aid rendered should be effective?
Same for a Divemaster. A certified divemaster is on vacation in wherever and sees a person in trouble underwater.
Does the divemaster have a duty to render aid?
Would a member of the public expect that Divemaster to render aid?
Does the public expect that aid rendered to be effective?
As divemasters and instructors we all thump our chests and proclaim loudly "I'm not acting in a professional capacity, I'm on vacation, therefore I can't be expected to be in charge". But it may not be so cut and dried, because we also proclaim loudly "I'm a divemaster, and I want the professional courtesy due my rank and station", when a visiting divemaster gets treated like one of the herd on the dive boat.
Cops are never off duty, even if they aren't in uniform. If you don't believe that, just ask one. I personally don't think that Divemasters should be held to the same high standard as a police officer, but maybe the public does.