Cute, but not for long
I happen to think the defendant is a loon, but this sort of case was never going to fly. The Internet, notoriously, interprets censorship as damage and routes around it. Doesn't matter whether the 'censorship' is 'good' or 'bad'.
The really interesting cases will start when people start making these guns and hurting themselves or others. I predict an upswing in hand and facial injuries as the first experimenters discover that machining parts to close tolerances is, uh, quite important if you want that explosive projectile to go in the direction you want.