I find it hard to believe that Popular Science would make such a mistake, but the author has reinforced the mistake by starting the article with “The dark side of the moon, despite its name, is a perfect vantage point for observing the universe.”
But all the quotes from scientists correctly say “far side of the moon”.
I know this isn’t really “science news” but I couldn’t find any other community to share this.
Logically you are correct, but human vernacular language rarely confirms to logic.
This is the correct answer. Language often evolves. I had never thought of the dark side as the side unexplored. It was always the side facing away from earth. That’s clearly what the author meant.