A.19.CPM:10 - Rationale

1. Set‑valued by design: partial orders are common in multi‑criteria settings; pretending they are total creates false certainty and brittle decisions.
2. ComparatorSet gating: declaring which comparisons are admissible, and under what scale or evidence rules, prevents “algorithm by convenience”.
3. Tri‑state guards: explicit pass|degrade|abstain preserves epistemic honesty: unknown is not silently converted into an outcome.
4. Strict distinction: separating compare from score and select prevents hidden semantic coupling and improves evolvability (methods change via wiring; kernel stays stable).
5. Single governing pattern: keeping one governing pattern eliminates near-duplicate comparison descriptions that drift apart and destroy usability.