You are correct that it is just a preliminary injunction. However one of the criteria a judge must apply in granting a preliminary injunction is that there is a high probability that the plaintiff will ultimjately succeed on the merits of the case. Put simply, she has said there is a good chance she will find for the Feds.
THE ACLU now runs and decides things not US. I see BIG problems ahead and I’m all for making BIG PROBLEMS ahead.