Bekenstein–Mukhanov area quantization confronted with the ringdowns of 33 binary black holes

If the horizon area of a black hole is quantized in units of αP², a Kerr hole can emit or absorb a graviton of azimuthal number $m=2$ only at the frequencies ωₙ=nακ/8π+2ΩH. Foit and Kleban proposed that the dominant ringdown mode of a merger remnant sits on the $n=1$ line, so that F=8π(ω₂₂₀-2ΩH)/κ, which in general relativity depends on the remnant spin alone, equals the same α for every remnant. We test this with the parametrized ringdown posteriors released with GWTC-5.0 for \ binary black holes, using Savage--Dickey Bayes factors that bound the posterior density conservatively where the samples run out. All four proposed values, α=4ln2, 4ln3, 8ln2 and 8π, are excluded, with ln B≤ for the first three and ≤ for 8π; GW250114 alone gives ln B≤ for each. A universal α survives only between \ and \ (90% credibility), where the quantized ringdown fits the data as well as general relativity. The window is fixed by the remnant spins: the two frequencies coincide at χf=, and % of the \ binary black holes in the catalog have median remnant spins between $0.6$ and $0.8$. A ringdown as precise as that of GW250114 from a remnant with χf≈0.55 or $0.85$, where the surviving α predicts frequency shifts of % and %, would close the window. If any line n is allowed, no single event disfavors the three smaller values by more than ln B=-.