Left: ΛCDM predicts satellite galaxies are accreted from random directions along dark matter filaments, producing an approximately isotropic distribution. The dashed circle indicates the predicted DM halo extent. Right: The observed Milky Way satellite system forms a thin, kinematically coherent plane — the "vast polar structure" (VPOS, Pawlowski & Kroupa 2020). Green arrows indicate coherent orbital motion within the plane. This is naturally explained if most satellites are ancient TDGs from a past interaction. The substrate framework explains both the planar distribution and the satellites' apparently high dark matter content: boundary parity physics produces MOND-enhanced dynamics in every baryonic system regardless of formation history.