The article only states what the judge ruled, it does not quote the law itself.
However the law does indeed define a firearm as follows:
"Firearm” means a gun that discharges a projectile or shot by means of an explosive, a gas, or compressed air."
The law, as they say, is an ass.
Aren't fools so ingenious. If the court doesn't get you your represenative will. We are safest on holidays when neithe is in session.