Nice find!
He does your entire back and forth (but in a lighthearted fashion ), stresses on the statistical impossibility to have non chalav treifa
Thankfully, he isn’t contemptuous and derisive of the valid points in a big bad “tumult”
but concludes with the obvious answer, we don't need to look at the entire milk mix, we can pasken on every individual cow that it produces kosher milk, so we now we have a mix of 100% kosher paskened milk.
Obvious my foot
If after the animals in the market were sold a lung was discovered to be a treifa they may be eaten because of כל דפריש.
If somehow all that meat ends up in one location, and I now know that there is certainly meat here which is treif, would we not recalibrate even though every individual piece already received it’s “psak”?