don't know, but you could probably email the lawyers that wrot e this blog post and find out. contact information for various ACLU lawyers is listed in the filing [1] found on the blog post.
Is it possible for someone not on the no fly list to join the lawsuit? No US citizens can find out whether they are on the list short of being refused (being on the list does not guarantee refusal, and refusal does not guarantee being on the list).