A scientist who shares a potentially harmful invention with the rest of the world might not necessarily lack ethical concern. If I invented the knife, I could choose to think that sharing it with others would increase the probability of random stabbings and accidental self-inflicted injury (very bad), or I could choose to focus on the fact that it would be an extremely useful tool in everyday life (very good).
A scientist who shares a potentially harmful invention with the rest of the world might not necessarily lack ethical concern. If I invented the knife, I could choose to think that sharing it with others would increase the probability of random stabbings and accidental self-inflicted injury (very bad), or I could choose to focus on the fact that it would be an extremely useful tool in everyday life (very good).