What if the powers that be decide to "classify" the results/reports? I would guess that would be a big legal hurdle. But if things get to that point, a copy the report would probably show up on wikileaks... I guess?
They could try passing a law outlawing security research, but: good luck with that.
http://en.wikipedia.org/wiki/Born_secret
The NSA isn't going to swoop in and claim that the results of the Truecrypt audit were born secret. But the answer to nabla9's question is yes, legal precedent exists in the United States for restraining the publication of original research when it is perceived to damage vital national security interests.