An attacker can already do this, at scale. Whether it be overriding traffic lights to show green in all directions, or taking down critical air traffic control

An attacker can already do this, at scale. Whether it be overriding traffic lights to show green in all directions, or taking down critical air traffic control systems. It’s like arguing that we can’t possibly build autonomous cars because then someone might turn it into an autonomous bomb. Keep in mind that solving this is “worth” about 40,000 lives a year in the US - nearly $1 trillion in economic damages a year in life and property. Bad things can always be done with good tools. As always, you provide layers of protection that make sense and in the end must rely on the underlying fabric of civilization to persevere.