Asteroid collisions actually happen all the time. Those collisions are usually the way objects leave the asteroid belt to go hit a planet. The system overall is not as stable as you might think.
Gravitational forces of asteroids on each other are negligible, other than the real biggies like Ceres, or binary systems right next to each other.
That article is a bit odd. For example, the claim that we only do asteroid discovery and not follow-up for orbital changes is absurd on its face. If an orbit changes then detection systems will perceive it as a new asteroid, and it will stop appearing in predicted locations. The broader point - that this is a technology with perhaps too much power, like what if nations shoot asteroids at each other, is a bit more valid but still far-fetched.
Gravitational forces of asteroids on each other are negligible, other than the real biggies like Ceres, or binary systems right next to each other.
That article is a bit odd. For example, the claim that we only do asteroid discovery and not follow-up for orbital changes is absurd on its face. If an orbit changes then detection systems will perceive it as a new asteroid, and it will stop appearing in predicted locations. The broader point - that this is a technology with perhaps too much power, like what if nations shoot asteroids at each other, is a bit more valid but still far-fetched.