The Exclusion Interaction in Relativity of Matter: Constitutive Saturation and a First-Passage Theorem

The Relativity of Matter (RM) programme uses the name Exclusion Interaction for a constitutive principle: as a physical channel approaches its finite admissible capacity, continuation through that same channel becomes progressively harder and is excluded at the capacity boundary. This note separates that canonical principle from one dependent operational consequence. For a fixed local stochastic transport process with generator L_loc and a positive cadence map d tau_cad = N dT, the universal-time mean first-passage problem obeys L_loc Theta = -1/N. On a frozen spherical background, the correction is exactly a positive weighted average of 1/N. The note distinguishes the canonical principle from candidate constitutive realizations, gives a counter-audit against placing N inside the divergence, states the weak solar scale of the effect, and lists explicit failure conditions. It does not claim a stellar calibration, a replacement of standard radiative diffusion, a nuclear-fusion mechanism, or a completed strong-field model.