That is not how it went. The official line was that it was not airborne, and that if it were, masks wouldn't help. It turned out they were relying on a definit

That is not how it went. The official line was that it was not airborne, and that if it were, masks wouldn't help. It turned out they were relying on a definition of "airborne" that only applied to tuberculosis. It really is airborne by an actually useful definition, in a way where masks can help. (And, incidentally, where those clear plastic barriers at stores don't.)