A cumulative no-go argument is presented for metric-distortion propulsion based on the systematic audit of five mechanisms proposed to relax the Quantum Inequalities (QI) of Ford–Roman [4]. Prior work [1,2] established a 15-order-of magnitude gap between the negative energy density produced by the standard Dynamical Casimir Effect (∼6 × 10−50 J for 20 modulators at 150 kHz) and the Ford–Roman limit for the toroidal geometry studied (|ρQI| ≈ 183.3 J/m3, Etotal ≲ 187 J). The five audited mechanisms are: (1) standard DCE with vacuum coupling; (2) non-minimal coupling ξ in Xenon plasma via the Gordon metric; (3) Lorentz Invariance Violation of the Myers–Pospelov type; (4) ultra relativistic plasma with high plasma frequency ωp; (5) Doubly Special Relativity (DSR) with a Planck minimum length. An independent analytic refutation is derived for each mechanism using distinct theoretical tools and sources of evidence. The central result is that the 15-order-of-magnitude gap is robust: no mechanism within known physics and current observational bounds can close it. For the LIV case, an explicit derivation shows that the correction to the QI is of order (E/MPl)2, requiring E ∼ 3 × 107MPl to close the gap—which is physically absurd.