They can blackmail and threaten members who have either revealed secrets of their personal lives, or they can harass people who they can find contacts, family members and such, but when it comes to outsiders, they got nothing. This is why criticism of Scientology is so effective, they can only hurt the people who were dumb enough to let them.
People who were never involved with their cult, never gave them contact information, never gave them materials as bargaining chips, are untouchable.
If you were never a member and piss off the organization, guess what? They can’t sue you, not without exposing themselves to greater scrutiny. Scientologists are the best example of Streissand effect suppression strategy gone wrong. They’ll never counter propaganda with more propaganda.