The way magic numbers and curves are elected is not a naive process.
The obvious backdoor in Dual EC-DRBG is a good example, and you have companies helping the NSA in very extensive ways (e.g. Crypto AG).
It's just logic, the goal of the NSA is to protect interests of the US, if it involves pushing rigged / weak algorithms for the greater "good" (at least from a US perspective), they'll do it.
It's legal, and logical.