Ironically there is a far greater chance of an NSA backdoor in propriety software from Microsoft or Apple than in SE Linux or Security Enhancements for Android.
The latest revelations makes either choice unwise.
The NSA cannot be trusted to be acting in good faith in ANYTHING it produces. Mathematicians/engineers who have done this kind of subterfuge should be deeply ashamed with themselves, producing error-ridden material and/or knowingly broken mathematics as your "best effort contribution to human progress" is about as low as you can go on the scientific ethics scale.
It appears that NSA is not in the business of national security, but in the business of mass surveilance and subversion of good, public crypto. Their "recommendations" of any specific constants or crypto techniques should be seen in this light.
I don't think they particularly care about Bitcoin - they might if it ever becomes significant in the international trade - but Bitcoin may become a collateral damage if secp256k1 was in any way influenced by the NSA shills at SECG. If secp256k1 does not include nothing-up-my-sleeve numbers, we have every reason to ask for an expert review.