The article doesn't make any effort to explain the orbital mechanics and ultimate dynamics of a Kessler Syndrome. The assumption I think you're making is all d

The article doesn't make any effort to explain the orbital mechanics and ultimate dynamics of a Kessler Syndrome. The assumption I think you're making is all debris remains in a fairly localized decaying orbit, which is not the case when a high energy collision occurs. The debris will fan out in two radial smearing patterns that loop back around at the collision point. Some pieces will hit more atmo for longer periods while others will achieve higher altitudes for a time and those can debris fields last longer. Should a LEO cascading collision event happen we would see lots of debris fields reaching higher orbits and a non-zero risk of those satellites being hit too.