Then how do you account for the "a universe that began as a remarkably smooth, superhot soup".
Soup has mass - and mass is supposed to be subject to the speed limit.
It's like blowing up a balloon. If you put dots with a marker on the surface and then blow it up, the distance between the dots increases as the balloon expands, even though the dots don't move. The massless fabric of space expands, the mass doesn't move.