This article is so full of fillers and off-topic references. Only one quote at the end mentiones quadrocopters. Other stuff is a plain text mentioning supposed fire from the sky and supposed weird wounds left by something like nails.
Only two paragraphs are dedicated to what is one of the problems in creating a shooting drone - recoil, and that a 9kg drone could be okay for that in their own opinion. And, piecing together what author wanted to say but failed to, we add there a special nail-like bullets from before, meaning special weapons where recoil may be lowered to somehow tolerable levels. Our usual weapons are meant for us, 60-100kg humans staying firmly on the ground, that can't be said about copters. But they are probably overestimating the precision that can be achieved by rotors while in the air - current stabilization is okay for photography, dropping bombs down, but reliably shooting something at distance without a special homing munition is another challenge that is hardly probable just yet. And if they spam whole magazines of ammo just to hit something, that precision is even less possible to achieve because, again, recoil grows.
Therefore, I call it a gossip that needs further proofs. This article is inconvincing and seems made to intentionally confuse the reader with how it jumps around and has content about drones spread very thin and far between.