Reasoning
Black holes made by a ~10^17+ eV cosmic ray striking a nucleon at rest inherit large centre-of-mass momentum: typical speeds are near c, vastly above Earth’s 11.2 km/s escape velocity, and a neutral TeV-mass black hole has too small a cross-section to be stopped by Earth’s column density. So the naive argument (“cosmic rays have not destroyed Earth”) has a real loophole for NEUTRAL stable black holes: nature’s versions leave, while LHC pair-production near threshold yields some below escape velocity that stay. G-M close it: white-dwarf interiors (~10^6 g/cm^3) and neutron stars (~10^14 g/cm^3) present column densities sufficient to stop even relativistic TeV black holes produced by cosmic rays impinging on their surfaces. Hence such bodies must have been accumulating trapped stable black holes for >=1 Gyr, and their observed survival bounds the trapped-growth scenario that the LHC could realize on Earth.
Verdict (step 6)
approved / checked. Reconstruction: (P1) cosmic-ray-produced neutral TeV black holes are relativistic and above escape velocity, with cross-sections too small for Earth’s column density to stop — so Earth’s survival cannot bound the trapped-slow case; (P2) WD interiors (~10^6 g/cm^3) and NS (~10^14 g/cm^3) present enough column density to stop even relativistic ones. Conclusion: WD/NS have accumulated trapped stable black holes for >=1 Gyr, so their survival substitutes as the empirical bound. Conditional on P1-P2 the substitution goes through: same object class (neutral stable TeV BH), same trapped end-state, denser host — no undercutting defeater found (the “cosmic rays reach WD surfaces” worry, e.g. magnetic screening, is a premise-truth issue handled by restricting to low-B WDs, priced at step 8, not a validity failure). Elementary kinematics + column-density comparison, traced directly.