I have seen nothing that would make me believe there is a "[gag] by the NSA" preventing frontier labs from publishing cryptographic results.

We published HAWK and McEliece attacks no problem.

The conspiracy theory going around the Internet is that they (the AI labs) broke cryptography in some way a la last season of HBO's Silicon Valley, and they're keeping the results under wraps until they can steal Bitcoin out of Satoshi's dead wallets, and then use that to pay for GPUs et al.