This is a non-story? secp256k1 was a reasonable choice at the time, the NSA curves had the NSA smell about them and didn't purport to be better. Now it turns out that they likely would have been ok after all, but it doesn't matter, the alternative chosen has been working fine. In secp256k1 there are various implementation hazards but you just have to be careful. Not sure if the NSA curves had the same hazards.