The second sentence of the article says that it's being used on visa applicants, who are therefore trying to enter the country legally. If CBP is already aware that someone has or is attempting to enter the country illegally, they don't need to analyze their social media.
Also, "illegal alien" is an outdated term because implies an individual's entire existence as "illegal," which is dehumanizing.
Also, "illegal alien" is an outdated term because implies an individual's entire existence as "illegal," which is dehumanizing.