Upward Trust and the Motive Gap in the Zoo Hypothesis: A Recursive Non-Extermination Rule for Hidden Cosmic Hierarchy

The zoo hypothesis explains the Great Silence by suggesting that advanced civilizations may observe younger worlds while avoiding open contact. Its weakest point is motive: why should overwhelming power restrain itself? This preprint proposes ultimate trust, an upward-facing restraint principle. A non-final civilization may preserve weaker civilizational continuity not from kindness, but because it cannot prove that no stronger power could one day judge, contain or erase it by an analogous rule. The argument reframes non-extermination as recursive self-preservation under uncertainty, and clarifies when restricted preservation may be more coherent than erasure in zoo-like explanations of the Fermi paradox. The manuscript is intended as a conceptual contribution to discussions of the Great Silence, the zoo hypothesis, hidden cosmic hierarchy and civilizational restraint.