The census is a direct presence/absence measure. If direct sale of bats or pangolins at Wuhan markets were the transmission route, those taxa would have to appear in a 47,381-animal survey; their total absence makes that specific direct-sale route unlikely. But the market-spillover hypothesis does not require bats/pangolins on site: it runs through susceptible farmed/traded mammals (raccoon dogs, hog badgers) that the same census confirms were present and were themselves plausibly infected upstream in the fur/wildlife supply chain. So the absence discriminates among sub-variants of the zoonosis hypothesis (narrowing to an intermediate-host route) rather than counting against market zoonosis as a whole.
Step 6 verdict — approved, checked
Reconstruction. P1: a 47,381-animal census of Wuhan market sales records no bats or pangolins but does record susceptible mammals (raccoon dogs, hog badgers). P2 (hidden): a direct bat- or pangolin-to-human market route entails those taxa being on sale, whereas the intermediate-host variant of market zoonosis entails only that a susceptible mammal was on sale. C: the absence lowers the likelihood of the direct routes while leaving the intermediate-host route untouched.
Traced load-bearing step. Pure entailment bookkeeping: the observation contradicts a necessary condition of one sub-hypothesis and no condition of the other, so it discriminates within the zoonosis family rather than against the family. That step holds conditional on P1-P2, and the statement is already scoped to exactly the sub-hypotheses whose necessary conditions are touched — no “refutes market zoonosis” overreach to correct.
Defeater probe. The obvious candidates — the census covers 2017-2019 and not late 2019, and it surveys sales records rather than exhaustive on-site presence — attack the truth/completeness of P1, not the link from P1 to C. Under step 6’s validity-not-truth rule these are step 8’s to price. No undercutting defeater found.