I agree, they don't do a fantastic job of justifying the title. However, #1 and #2 are related, and the article does try to explain why they cause less safety. More people biking means both fewer cars, and people driving cars are more aware of bikers.
> Safety in Numbers is a straightforward concept: More people on bikes creates safer conditions on our streets. The National Association of City Transportation Officials (NACTO), which represents professional planners from 81 cities from around the United States, pointed this out in their own pushback on NTSB’s recommendations.
If you follow the links in the article you'll come to some actual research about the topic https://www.bmj.com/content/332/7543/722.2.