Resolution of the IceCube PeV Neutrino Anomaly via Substrate Torsional Relaxation: Non-Hadronic Acoustic Shear Emission and the Elimination of the Diffuse Gamma-Ray Saturation Conflict

The IceCube Neutrino Observatory has established an isotropic diffuse flux of extraterrestrial neutrinos spanning 100 TeV to multiple PeV. In standard multi-messenger astrophysics, these neutrinos are attributed to hadronic interactions (pp or pγ), where isospin symmetry strictly dictates that charged pion production (π± -> μν -> eνν) is accompanied by neutral pion production (π0 -> γγ). The resulting cascade gamma-ray flux must accompany the neutrino flux; however, Fermi-LAT measurements of the isotropic diffuse gamma-ray background (IGRB) reveal that blazars already saturate the gamma-ray budget, leaving no room for the cascade radiation mandated by IceCube neutrinos. Standard resolutions invoke ad-hoc "choked" or "hidden" sources that trap photons while releasing neutrinos. Building upon our foundational series on the physical vacuum as an elastically pre-stressed continuum, we show that PeV neutrinos are produced via direct, non-hadronic torsional shear relaxation of the pre-stressed vacuum substrate. In our ontology, neutrinos are unbound transverse torsional shear wavepackets (∇·u_ν ≡ 0) carrying non-vanishing circulation. In extreme cosmic accretion vortices, the substrate accumulates rotational twist until localized shear stress reaches the holding pre-stress P_0 ≈ 7.48 × 10^24 Pa. The medium relieves this strain through direct acoustic shear peeling, radiating PeV torsional wavepackets without intermediate neutral pions (π0 ≡ 0). We analytically derive the neutrino energy spectrum dΦ_ν/dE ∝ E^-2.5 and prove that the accompanying cascade gamma flux vanishes identically (Φ_γ^cascade ≡ 0), completely resolving the IceCube–Fermi-LAT multi-messenger crisis under Occam's razor without fine-tuned source models.