If all 33 of the cases exhibit these microbleeds, then you have a problem since the likelihood of all those cases just happening to match your 1000psi criterion for handgun BPW effects is really slim. There will definitely be cases in there where the pressures involved are not adequate to match your threshold for BPW requirements.
Credible criticism of a published theory should at least demonstrate a working understanding of the theory. Does the published theory predict that GSWs to the chest below 1000 psi will not exhibit distant wounding effects, or that distant effects above 1000 psi will be more likely and easier to see? Your reasoning is analogous to claiming that a published analysis predicting broken legs are more likely for falls above 5 feet is contradicted by reports of broken legs from lower heights. Your reasoning is analogous to claimimg that a published study predicting lung cancer is more likely for smokers of two packs a day is contradicted by findings of lung cancer in smokers of one pack a day.
Anyway you have specified that a positive finding on the Military Acute Concussion Evaluation (MACE) in the presence of a GSW to the chest is indicative of mild traumatic brain injury which (in the absence of other factors) has to be from the BPW. That's fine, let's go with that.
MACE can be useful tool for helping to diagnose mTBI, but I don’t think it can provide solid confirmation of remote brain injury due to ballistic pressure waves from well-centered chest hits, because in nearly all cases of center chest hits with large enough BPW to expect mTBI, ischemia/reperfusion will be a confounding factor in surviving patients. The simplest way to eliminate ischemia/reperfusion as a confounding factor is to focus on cases where the GSW caused rapid death as in the human autopsy study and your suggested approach to a deer study. MACE might be useful in telling us whether GSWs to the chest can cause mTBI, how can it distinguish the BPW mechanism from ischemia/reperfusion?