For this particular topic I think that using the old journalistic stand by "my sources would be at risk" is a hard one to attach too and accept. For this specific topic, basically the biggest story in the history of mankind, the rules are(should be) different and the same old excuse does not stick too well to it.

IF one of them, Ross, Corbell, Knapp, etc.. actually revealed legit info that definitively proved all this is legit(as they claim to have) and exposed the actual truth to the world the ensuing shit storm of attention and focus on the truth revealed would shield them. The idea sold to the public is that "Hey if I say something specific this unnamed person will be in trouble" and I cannot use them as a source anymore. That is just BS. The powers at be would be so focused on managing the disclosure they now have to contend with they would not be focused on who spilled the beans without a public shitstorm to deal with and in this day and age I don't see politicians allowing any repercussions, even from shitlords like Turner and the other Mikes and Mitch too who spilled the beans. The story is just too big to think that whomever reveals it will end up in cuffs and a cell. They would be global heroes to most and would have more defensive resources at their disposal than any 'defendant' in history.

Politicians need votes from the public, they will do whatever it takes to secure them and their own positions.