The translation you quoted is incorrect: “At the end of the discourse, the thief who was steadfastly keeping his mind on the arising and perishing of the aggregates discerned the impermanent, unsatisfactory, and non-self nature of all conditioned things and soon attained Sotapatti Fruition.”
- “Anicca, dukkha, anatta” characteristics do not refer to an “impermanent, unsatisfactory, and non-self nature” OF THE aggregates (panca upadanakkhandha).
- The point is that cultivating panca upadanakkhandha (which is the same as engaging in apunna/akusala kamma) is unfruitful (anicca) and takes one away from Nibbana (dukkha). Thus, that engaging in such actions is useless and of no benefit (anatta.)
This is a bit of a deep point to think about and understand.
- It takes an effort to understand this: “Sotapanna Stage via Understanding Perception (Saññā).”