I don't think it needs that much explanation. The New York Times and other institutional press have often done this same thing. Which is, they report from "cred

I don't think it needs that much explanation. The New York Times and other institutional press have often done this same thing. Which is, they report from "credible" sources without physical evidence of any kind. A source is considered credible by how much clout it carries with other major institutions or because of a history of trust. i.e. Even though intelligence and the military get things wrong all the time even to the point of outright lying, they are "credible". This has lead them astray many times in much more significant matters. Once reported, they treat contrary evidence as innuendo in all but the most severe cases of contrary evidence. I think they only bothered with a significant retraction effort here because the evidence of their error was so compelling and public.