Why do Mormons say black people will enter Heaven only as servants?

OK, everybody knows how the LS Church used to deny the priesthood to African Americans until 1978, and then they defend themselves saying that "God revealed" that the teaching was repealed. Mormons love to say "Blacks have always been accepted in the church" But what no one talks about is the type of acceptace that Mormons refer to when they say that. Why did Elder Mark Roberts say: "In spite of all he did in the pre-existent life, the Lord is willing, if the ***** accepts the gospel with real, sincere faith, and is really converted, to give him the blessings of baptism and the gift of the Holy Ghost. If that ***** is faithful all his days, he can and will enter the celestial kingdom. He will go there as a servant, but he will get celestial glory"? That had nothing to do with the priesthood revelation. Mormons still privately believe that black people will be servants in heaven.