Buttigieg's two black children are slaves?

Tucker Carlson, in his interview of Milo Yiannopoulos, likened lawmaker Pete Buttigieg's adoption of two black children to 'slavery.' What psychological prompting led Pete and his husband, Chasten Glezman, to do that? Is there some connection to the plight of black Africans at the hands of white slave owners in America's history? Both Pete and Chasten were raised as Catholics but converted to Episcopalian Christianity.