Zero whistleblowers does not mean a secret was kept, just that those that knew didn’t care to blow a whistle. Not important enough.
“Not important enough”
For who?
The Japanese-Americans who got hauled off to camps for years?
The folks who did it were ashamed of what they did (after the war) and were afraid they would become social outcasts (at a minimum).
It was very important to the secret-keepers. That is why they took the secret to their death bed.
I wish you could convince the military industrial complex that the classification system should be abolished because it “does not work”.
Imho they would all laugh you out of the room.