The question was put: "Which, to your mind, is the least absurd explanation for the Priesthood ban? (1) Some factor from the pre-mortal existence determined that certain spirits, once placed in mortal bodies, could not have the Priesthood after ~1850 and until 1978. (2) Some ancient action caused God to place a curse on a certain people, and their modern descendants could not have the priesthood until 1978; (3) There is another more logical explanation that still maintains the divine origin of the ban."
To which I responded:
I chose the last option. Although it, too, is absurd, it is the LEAST absurd of the three. A much more plausible explanation is that the ban was not devine at all. JS had it right and BY's racial prejudices caused BY to get it wrong. Continuing racial prejudice, combined with irrational fear of the consequences of declaring BY to be in error, combined to perpetuate the ban until it was removed in 1978. Even then, Spencer W. Kimball did it very creatively, avoiding any admission that the ban was wrong.