Mormons literally rewrote and ignored their own doctrine to update it for Progressive Politics around racial relations in 1978. And have spent the decades since pretending to not even understand why it was that way to begin with.

Heck their entire religion is based on and believes that you can just receive divine inspiration at any time from God, and that becomes doctrine for either the entire church or you. It is 100% possible for the father to have been given a "vision" from God about it and that comes before all things.

Not that I actually think he is lying in this case, but Mormons aren't some rigid upstanding denomination in the way you might think.