As usual, the real purpose of the lawsuit is buried DEEP in the article (hey, at least it's there, right?). This isn't about religious freedom -- the ACLU care nothing for that, it's about lawyers not being able to get their advertisements to prisoners. Gotta let these guys know all the possible law suits they could file to game the system, don'cha know.
Actually, all of the lawsuits filed by the ACLU are about the ACLU getting their legal fees paid, even if they lose. It’s called full employment for liberal lawyers.