reasoning
The second residual genetic observation Stansifer retains is SARS-CoV-2’s strong affinity to bind human ACE2 relative to other species — a feature more expected if the virus were adapted/selected on human-ACE2 systems (lab) but also compatible with a well-adapted natural spillover. He assigns a Bayes factor of 2 in favor of LL (log-odds +0.69), and caps the possible strength at 14 because the deep-mutational-scanning study compared only 14 species, so the affinity could be at most 14x more surprising under zoonosis. This is a minor contributor swamped by the location factor. (Descriptively references the ACE2-binding finding whose empirical basis belongs to the receptor-binding primary sources.)
Verdict (step 6)
Reconstruction — Premise: among the 14 species in the deep-mutational-scanning study, SARS-CoV-2 binds human ACE2 most strongly. Load-bearing step: strong human-ACE2 affinity is more expected if the virus were adapted/selected on human ACE2 (lab), so it favors LL; and the likelihood ratio is bounded at 14 because only 14 species were compared. Evaluation: the cap logic is sound — model the best-bound species as roughly uniform over the 14 tested under zoonosis, giving P(human best | Z) ≈ 1/14 vs ≈ 1 under human-ACE2 selection, so BF ≤ 14; the direction likewise holds conditional on the premise. A survivorship counter-explanation (any pandemic virus must bind human ACE2 well) challenges the premise’s evidential force, not the inferential step, and is priced in steps 7-8. BF-2 magnitude not judged here. Approved, checked.