This is complete bullshit, by someone who has a fixated idea but knows nothing.
At 70 break distance is longer, time to react is shorter, and collision speeds are higher. All factors that increase danger and damage.
You might as well claim that driving 250 is perfectly safe if everybody do it.
Obviously acceleration as in negative acceleration is greater in Collisions at higher speeds. You are either a troll or a very very illogical person.