Not long ago the CDC itself was saying that mammals couldn't catch this strain of avian flu and we had nothing to worry about. Then they found a few milk cows believed to be infected, but they assured us it couldn't kill cows and that the infection couldn't be transmitted through milk.

Where along the way did we go from scientific knowledge that it couldn't jump to humans to only quacks believing such nonsense? More importantly, where are the controlled studies proving transmission from infected birds to humans?

Proving transmissibility of such a pathogen would require something along the lines of Koch's postulates. Unless I missed something extremely important, we haven't done this type of study yet.