There are claims now that Joseph Smith ordained a black man to the priesthood. I am leery of "new discoveries" about church history that come forth now because where the vast bulk of them come from is turning to the churches enemies to get a "fuller story", which is like asking Laman and Lemuel to tell us all about Nephi, or asking Judas to tell us about Christ.
But either way, if Joseph Smith ordained a black man to the priesthood does that make any difference for the prophets that followed him?
If we have paid a bit of attention to the gentiles in the scriptures then we would know that during his mortality Christ was addressed by a Gentile woman and refused at first to even respond to her request. When he did so, he said he was not sent but to the lost sheep of the house of Israel. He only granted her request when she posed it in terms of dogs receiving the crumbs that fall from their masters table.
Christ also didn't send his disciples to preach among the gentiles and gentiles were not allowed to be baptized. Note that was while Christ himself was living at the head of his church.
Then, Christ gave a revelation to Peter and gentiles were allowed to be baptized, and were actively taught the gospel.
BUT. Hundreds of years before that there was a gentile woman by the name of Ruth. We do not get a meaningful account of her faithfulness. But it was such that the prophets of her day included a tidbit about her. Ruth was given the honor of being the ancestor of the Son of God himself - an eternal honor far greater than the temporary miracle the gentile woman requested of the Savior.
Physical healings are temporary blessings limited to mortality. To be the faithful ancestor of the Christ is a blessing that will be held for all eternity.
But knowing a bit about the priesthood, we know Ruth received whatever she received by revelation.
And just so, if it is true that Joseph Smith ordained a black man, then we know he did it under authority by revelation. But Joseph Smith himself openly taught that blacks were cursed to not have the priesthood. Nevertheless, if it really was the case that by special revelation Joseph Smith knew the Lord felt one of them was to be an exception, just as the gentile Ruth was, then we have faith in Joseph Smith and his revelation and authority just as we do in Brigham Young and his revelation and authority.
And it was by revelation and authority Brigham Young, as well as the prophets that followed him knew that if there really was an exception, then that exception was not to be the general case until the days of Spencer W Kimball when the Lord offered the priesthood to all mankind who have ever lived on the earth.