That's it! I knew about the v1.1 condition system but never thought about looking there.The "debilitated" wording is a holdover from the v1.1 Nausea Status Track. (Queasy/Sick/Nauseated/Debilitated) "Nauseated" had the PC spending one action vomiting, and "Debilitated" increased that to both actions.
1.2 pared the Status Tracks down to a smaller set of two-tiered conditions.
So Radiation poisoning would result in an Illness that hampers your PC with the SICK condition until they are either cured through treatment, or their END pool depletes, leading to DEATH.