There may be a flaw in that analogy, as I see it, because moving from 2D to 3D implies pre-existence of an individualized soul. If all souls are already created, how would an OP "get" one. It's also possible that we are confusing ourselves with terminology, or don't have the proper grasp on the terminology we're using? I suggest that because it may be possible for an OP to become souled in some way.I believe that just as a second-density being can become a candidate for third-density in their interaction with us, so too can an organic portal develop the energetic foundation for an individualized soul to connect to, since the " terrain" has been properly converted.
I read Messages from Michael back in the 1990s, along with many other New Age tomes, but that one, I remember distinctly, made very little to no impression on me, FWIW.