Thats BS.
Point 1. Its not breaking the speed limit that can kill people. Its speed inappropriate for the conditions. Doing 70mph on the motorway in a monsoon leaving the highway code prescribed stopping distance is far far more dangerous than doing 80mph on a clear summers day on an empty motorway
You are correct in what you say, but in a built up area, doing 40mph instead of 30mph is considerably more likely to kill someone no matter what the conditions in the event of a pedestrian collision.
I am 100% for speed appropriate to the conditions, but many people drive way too fast in many built up areas.