The MOND Acceleration Scale from Horizon-Thermalized Mediator Freshness

The MOND acceleration scale a₀ ≈ cH/6 (Verlinde 2017) is derived here as a scaling, a₀ = ζ cH, from one mechanism: the freshness clause of Mediated Access requires the gravitational mediating sector to mix, and mixing needs a bath — the cosmological horizon at the Gibbons–Hawking temperature. The coefficient ζ ≈ 0.17 is at present measured, not derived. The falsifiable content lies in convention-free quantities: the locked RAR exponent, the constancy of a₀/cH across environments, and an epoch dependence carrying a feature near z ≈ 1.32. Keywords: MOND, modified gravity, radial acceleration relation, emergent gravity, holographic principle, Gibbons–Hawking temperature, galaxy dynamics, astro-ph.GA, gr-qc