A discussion on the comix-scholars list generated a note from Bart Beaty, author of Fredric Wertham And The Critique Of Mass Culture.
Just for the record, [no access to medical records] is exactly the arrangement that I made in 2002 when I was granted access.
However, do bear in mind that the LoC does not have the power to implement any policy with regard to these papers and that all decisions are made by the executors of the Wertham estate. I can assure you, having worked very closely with the LoC's extraordinary staff over a period of several years, that the librarians at the LoC would like nothing better than to make these papers available. But the decision is ultimately that of the executors, who have their own reasons for making their decisions.
Also, the way that the papers are organized, medical records are not all in one place, so they're not so easily redacted.
Ah, those extraordinary manuscript librarians - hear, hear!