I wouldn't be too surprised if a terrorist used a hobby aircraft against some building or group of people in the near future. It's just a matter of time. No nukes but they could use a small explosive package on board a multicopter. Some of the hexes can carry a lot of weight and certainly a grenade or two would be possible. But if we banned everything a terrorist could possibly use to create terror we would all be restricted to our residences and the National Guard would be patrolling the streets and airspace. With the terrorists it's all about news coverage. That's why they call it "terror".