He can get clearance to release certain portions of what he knows.
The persistence of the data depends on its classification level. If it is indeed, classified Secret or better, it would be a major legal issue if copies were located other than where authorized. The higher the classification, the more rigid the record keeping and procedures. Sometimes the raw data is not classified, but the summation connecting the dots is.
This does not preclude folks from ignoring the procedures regarding classified info (ala Sandy Berger), however, I would find it unlikely that some who did that, would go public.
One thing for sure, it will be interesting to see where this goes.