As I read it, the point of mentioning Dual EC is to show a previous case where NSA have acted in a way that reduces security for hand-wavy reasons, in addition

As I read it, the point of mentioning Dual EC is to show a previous case where NSA have acted in a way that reduces security for hand-wavy reasons, in addition to the DES case where they did the same. And now, in a world where QR + pre-QR algos are typically being introduced in a layered fashion, they're saying "let's add another option, to reduce the number of options" which at least looks very suspicious Practical quantum computers are probably not very close, but you can certainly use the fear of them as a chance to introduce a new back-door. If you did, you'd have to behave exactly as the NSA is doing right now.