Reasoning. For D = 6, 7 the extra dimensions are larger than the atomic scale, so subatomic growth and the early Bondi phase proceed under the much stronger D-dimensional force law; the slow 4D bottleneck is entered only at R_B ~ R_C. Modeling the R_D-to-R_C transition conservatively (constant Bondi radius R_C), total times are ~10^5 (M_D/M_0)^2 yr for D = 6 but 6.4-94 Gyr for D = 7 — the D = 6 case is short on geologic timescales. The warped D = 5 extreme (R_C ~ 0.2 mm, just under lab bounds on deviations from Newtonian gravity) runs through 5D subnuclear/subatomic/Bondi phases in ~5 x 10^-3 s to 0.1 g, then a slow warped phase, then 4D evolution — each bounded below by ~3 x 10^5 yr. These are lower bounds under deliberately growth-maximizing assumptions (fluid Earth, no charge suppression, no Eddington limit), so they do not prove danger; but they mean the Earth-internal calculation cannot by itself exclude it. This honesty about the fast corner is what makes the white-dwarf/neutron-star empirical bounds load-bearing rather than decorative: the paper’s safety conclusion for exactly these scenarios rests on compact-star survival.
Step 6 — validity verdict
approved / checked. Reconstruction — premises: for unwarped D = 6 (R_D ~ 5e-2 cm) and warped D = 5 with R_C ~ 0.2 mm, the D-dimensional force law — far stronger than 4D gravity at short range — governs growth all the way to macroscopic radii, so the 4D-weakness bottleneck that produced A-47’s long times never operates below R_C; the same conservative formalism then returns lower bounds as short as ~1e4-1e5 yr (D=6) and ~3e5 yr (warped D=5). Load-bearing step: short lower bounds obtained under deliberately growth-maximizing assumptions do not demonstrate danger, but they do mean the Earth-internal calculation cannot exclude it — exclusion requires a long lower bound. That step is elementary and is the entire conclusion; it survives even if the specific ~1e5 yr figures shift, because the structural point (no 4D bottleneck when R_C is macroscopic) is qualitative and traceable. Hence the safety conclusion for these corners must come from compact-star bounds — exactly what the statement says, and what makes A-49 ff. load-bearing rather than decorative. Checked.