Classical enumerations of the Karmendriyas list vak, pani, pada, payu and upastha in that order, and the order is worth pausing on precisely because it is not a ranking. Nothing in the Samkhyakarika or its major commentaries treats speech as metaphysically superior to excretion, or grasping as more fundamental than generation; the five are co-ordinate members of one category, distinguished by what they do rather than by how important the tradition considers what they do. This is a genuinely different posture from many other classificatory schemes, ancient and modern, that quietly smuggle a hierarchy of dignity into what presents itself as a neutral list.
Payu's equal standing with the other four Karmendriyas follows from the same production mechanism that generates all five: the sattvic aspect of ahamkara, undifferentiated by any judgment about which resulting organ matters more. Sattva's association with clarity and lightness applies to the eleven organs as a set, contrasted with the tamasic tanmatras, not distributed unevenly among the eleven themselves.
The absence of ranking also serves the system's larger argument. If liberation depends on buddhi's discrimination between purusha and prakriti, and every evolute without exception belongs to prakriti, then no evolute, however elevated or however mundane its function seems to ordinary judgment, can be closer to or further from purusha than any other. Payu is exactly as far from consciousness, in Samkhya's strict terms, as buddhi is, which is to say, entirely and equally far.