The difference is not in the complexity of the code, but the magnitude of the attack. You would need to subvert every DNS request from a certain client, for the duration of the TTL of all signature points. (Exactly how much harder it is depends on the circumstances, but a travelling target would be even harder than a well known stationary one, even if you control large parts of Internet infrastructure and is willing to use it.)

But that's not the point. The only point is that between it and the SSL CA infrastructure, the latter is the one NSA has more control over and a much easier time generating certificates for, so the labelling the former "NSA controlled" is slightly disingenious.