How you explained the abbreviation of his title makes sense, I hadn't thought of it that way.
What you say is factual, I am aware of need to know and that matters of national security should not be divulged to those that do not have the clearance.
I agree with what you've stated here and also that there's still a lot of ground to cover.
As for Corso's credibility, the story around Wisner is not based in fact. Corso's ego appears inflated or that he is given to ideals of grandeur to the point of falsifying facts to make himself appear more powerful than he was. He must have felt a need to stroke his ego, he is only human after all, but for me it detracts from his message.