Considering how fast Genesis forms, it is a far more logical and easier explanation that the Genesis-wave re-formed Regula.
No, it is not easier and more logical at all you are saying that the wave magically traveled to a planet that was pretty far from the detonation point and at what seemed to be light speed for some unexplained reason and still had the energy to completely reform it into a planet capable of supporting life.
The damaged Enterprise reaches the Nebula pretty fast. It's not that far away.
Besides, remember the shockwave in TUC?
Same author, same director.
That shockwave travels a far greater distance in a pretty short time.