Why? Georgetown did nothing illegal at the time, and there is a little thing in our Constitution about “ex post facto” laws.
Not only did Georgetown do nothing illegal there is a good chance those slaves were bought by other blacks.
There were THOUSANDS of blacks who owned slaves. There were 3,000 in New Orleans alone. There were black slave breeders. They sold their own offspring.
And there were thousands of whites who never had a slave.
Let’s not forget the the man who took his indentured servant to court to have him made into a slave. He was black.