Discharging a firearm into the sky isn't it. I don't know if I'd classify this as being as bad as shooting at a passenger plane, but the gun probably won't hit a plane 30k ft in the sky anyway, and the missed bullets/pellets (when you inevitably miss the plane or drone) will almost certainly kill someone if they fall on their head. I'd be disappointed if there wasn't a felony charge for doing that.
Whether the drones should be allowed is another question of course, but the potential collateral here can't just be brushed off.
A bullet that comes down has enough energy to kill someone. Shotgun pellets (especially smaller birdshot) would have much less energy when it comes down. That's why skeet shooting is the only kind where you shoot upwards. The terminal velocity of a BB is pretty small.
Birdshot would do less harm for sure, but that doesn't seem to be what the person in the article used:
When this didn't work, he went inside the home to retrieve his 9mm gun from a safe, came back out, and shot the drone, which was about 75 feet in the air at the time.
Having been skeet shooting, that wouldn't be nearly as bad to be hit by, but firing that off in a random neighborhood still has the potential to damage random people's property and is horrifically irresponsible.
Anyway, I was trying to emphasize that in no world is it acceptable to be firing live rounds in the sky, drone or not. I don't see how shooting a gun into the sky in a neighborhood is worthy of anything less than felony, given the potential damage.