This was probably an unpublished opinion (and I'm not sure, maybe all District court opinions are unpublished?)
But from the article we see that it doesn't really matter, as the subject opinion is merely quoting an earlier ruling from the 4th Circuit, which likely IS published. (I didn't take the time to look for it.)
"To be sure, in states like Virginia where individuals are permitted to openly carry firearms, ‘the exercise of this right, without more, cannot justify an investigatory detention.’ United States v. Black, 707 F.3d 531, 540 (4th Cir. 2013)."