Ok, lets think about this rationally.
I think most of us would agree that the greatest threat from small drones is to small single engine puddle-jumpers? Airliners have multiple engines, and as with birds, it usually needs a flock to bring one down.
Examples.
Man 1 has a bit of spare cash.
Man 1 buys Cessna 152.
Man 1 has great fun flying around.
Man 1 obeys all the rules and flies responsibly, yet unavoidably, the very act of him flying around imposes a small extra risk on those whom he flies above, and history shows that every now and then puddle-jumpers take down an airliner.....
Man 2 has a bit of spare cash.
Man 2 buys quadcopter.
Man 2 has great fun flying it around.
Man 2 obeys all the rules and flies responsibly, yet unavoidably, the very act of him flying around imposes a small extra risk on those who fly around him. He is vanishingly unlikely to take down an airliner, but he might take down a puddle-jumper.
Which should be banned? One, both or none?