I cannot for the life of me understand how anything relating to this can be held back at this point. Our intelligence methods and staff have had a several-times-over complete turnover, and most of the assets involved in those days are dead. There’s nothing that needs hiding any longer at this point — good or bad.
They are likely trying to hide things that would embarrass the agencies, not specific agents. Which is not a good enough reason to hide info from the public, frankly.