The point is that if the author of the article got on a bicycle with 100% certainty of being involved in an accident, I seriously doubt she would get on it without a helmet or some protective gear, despite her claims that wearing a helmet actually increases your risk of injury. Obviously if you knew you would get in an accident you wouldn't get on the bike. I'm convinced that it's the not knowing (and erroneous assumption that she is safe) that makes her comfortable not wearing a helmet, not a ironclad case that not wearing a helmet is safer than wearing one. If put in a position where she absolutely had to decide whether she would be in an accident with or without a helmet, I do not believe she would back up her claim and go sans helmet.
It's really not that different than most risks we take, such as unhealthy eating or exposing ourselves to ultraviolet radiation. We're immune to the danger until we're not.
As a person who doesn't wear/trust bike helmets, if the certainty of an accident on a particular ride was increased to 100%, I would choose to not ride the bike rather than trust the helmet to protect me in a collision. If I knew a brick was to dropped on my head at a certain time, I would reach for a steel helmet before a styrofoam one, but first endeavor to not be at the appointed place and time for a braining.
That's tragic, because this debate is about a tradeoff: a moderate benefits of exercise vs. a small risk of injury. I am a very regular bike commuter, and it is my main form of exercise, but collisions are very, very dangerous. I would not get on a bike in the case of 100% certainty of an accident. Helmet advocates focus on the risk of injury and tend not to consider the benefits they're trading off against, or consider how they are dissuading people from the benefits of cycling.
It seems like this boils down to an argument not to cycle as much as to wear a helmet.
It's really not that different than most risks we take, such as unhealthy eating or exposing ourselves to ultraviolet radiation. We're immune to the danger until we're not.