From the article, quoting the profiled professor: "Persuasion is based on emotion; it is not based on logic. If everybody knew that 1 percent of the [Twitter] accounts are responsible for 30 percent of the traffic, people would be more careful thinking about that. But the vast majority of people don’t know that. Information is propagated through retweets from others who are either fooled or agree. At the end of the day, people receive some piece of misinformation, and many will not realize that it has come from one account that has been blasting messages. They will think that it came from friends."

In other words, young people who have grown up in the Internet era still need to learn about checking sources, finding information sources off the Internet, and cooling their emotions and tribal allegiances before deciding complicated issues of social policy. That's not news to anyone who reads Hacker News regularly. Every political movement and every electoral campaign for public office has a tendency to try out various persuasion strategies, empirically, seeing what works by looking at the results of campaigns. Voters who are resilient to the spreading of rumors are still the best protection for free and fair elections. One thing that helps voters become more skeptical is the back-and-forth of competing campaigns, so I'm not sure that the "social media manipulation" mentioned in the article is any more inherently dangerous than the inflammatory political cartoons of the early nineteenth century.