Dynamic Harmony Structural Stress-Test Series. This paper evaluates the theory of biological organization based on closure of constraints developed by Montévil and Mossio. The analysis examines whether constraint closure provides a sufficient structural account of biological autonomy and the emergence of organized living systems. Using the Phase Non-Substitutability Test introduced in Paper 0 and the architectural boundary criterion developed in Paper 0B, the paper analyzes whether closure of constraints represents a genuine architectural redefinition of system organization or whether it remains a configurational arrangement within an existing state space. The analysis clarifies the relationship between constraint networks, biological autonomy, and the structural requirements for Type-2 emergence. This paper forms part of the Dynamic Harmony Structural Stress-Test Series, a research program that evaluates major theories of emergence across physics, biology, and complex systems through adversarial structural analysis.