The judge apparently didn't think much of them. While it's unusual for a national park to be a place for concerts, and Wolf Trap is I believe the only one (as the government argued), it's still a national park. Much like federal courthouses and other federal property, it's entirely within the domain of the feds to prohibit concealed carry, even under current Second Amendment jurisprudence.
It seems like a quixotic tilting at windmills thing to me.
I'm not going to say outright that it was stupid even to file the lawsuit, since I assume he had some ideological reason for it more than that he was in some kind of incel rage at not being able to bring a gun to a concert. But who knows?