Fair, but I still feel like the effect might be overplayed. Any impact is going to generate a lot of heat, and any debris is going to have a lot less structural integrity.
Let’s say you actually wanted to inflict Kessler Syndrome on an alien species. You’d find that the altitude makes the difference between hours and centuries of syndrome effect. Debris at 200-500km might get you a few months, whereas 1200-1500km might get you a few centuries. The difference would be atmospheric drag, right?
Kessler Syndrome is also a chain reaction. You wouldn’t deploy the material, it needs to already be there [in the form of satellites]. But modern practice is trending toward lower operational orbits for large constellations, isn’t it?
I feel like you’d need to deploy satellites with a pretty awesome combination of sheer throughput and sheer ignorance, in order to create the right conditions for a lock-in risk. Worst case, in our current situation, I feel like we would have occasional crashes leading to small localized debris clouds that mostly disburse without causing a cascade.
Why would anything else be more plausible is my main question. Why would so much material be in just the right altitude to cause such a dramatic effect? You’d just don’t build important things in such risky ways.