Any gunnery professionals can explain how does it EVEN works?!
Double-confirmed that M109, M777 and their munitions in CMANO doesn't marked air unit as valid, even missiles.
The U.S. Army’s Big Guns go to the South China Sea
Senior Army and Pentagon strategists and planners are considering ways to fire existing weapons platforms in new ways around the globe – including the possible placement of mobile artillery units in areas of the South China Sea to, if necessary, function as air-defense weapons to knock incoming rockets and cruise missiles out of the sky.
Alongside the South China Sea, more mobile artillery weapons used for air defense could also prove useful in areas such as the Middle East and Eastern Europe, officials said. Having mobile counter-air weapons such as the M109 Paladin, able to fire 155m precision rounds on-the-move, could prove to be an effective air-defense deterrent against Russian missiles, aircraft and rockets in Eastern Europe, a senior Army official told Scout Warrior.
Mobile air defenses such as an Army M777 or Paladin Howitzer weapon could use precision rounds and advancing fire-control technology to destroy threatening air assets such as enemy aircraft, drones or incoming artillery fire.
One of the platforms I supported in 2009 was a self-propelled 155-mm howitzer designed to supplement the XM777's capabilities and replace the M109 as a self propelled indirect fire platform. It carried a reduced load of ammunition to address weight restrictions for air transport, and maintained the kill power of "one shot one kill" smart rounds (essentially less amo, but more lethal with a typical combat load).
At that time, there were no rounds designed as anti-air weapons both because an indirect fire round's speed is significantly lower than that of a jet aircraft or worse, a missile, and because the smart targeting capability was a terminal event that didn't kick in until the round reached a specified distance from the firing platform and then searched for patterns of pre-programmed threats as the round fell to the ground.
There was an effort to include active armor capability on the platform, but that was designed to quickly fire at incoming munitions and missiles to either deflect or destroy the warhead before it impacted the vehicle. Engagements with the system took place in the final half-minute of a projectile's path toward the vehicle, with the detect, evaluate, fire, and hit time frame occurring in milliseconds before the round could impact the vehicle.
The article you cite sounds more like jingoism or perhaps a defense contractor's marketing pitch than solid military planning, at least in terms of what that planning consisted of in 2009.