I have to wonder — Did his father’s ancestor capture the slave that his mother’s ancestor bought? :=)
Unlikely, since Kenya is east africa and most slaves came from Ghana-Nigeria-Senegal-Gambia West Africa.
Unless you hold with the Frank Marshall Davis is his father idea, in which case it becomes possible.
African American slaves had ancestors who were African slaves. It was really unusual for (white) slave catchers to penetrate from the coast. Rather, blacks sold other blacks into slavery in Africa.
Ghana has as a tourist attraction some formerly Dutch slave forts. Their original function was to hold slaves brought from Nigeria to Ghana to work in Ghana gold mines. Only later were they used to hold Ghana slaves for shipment to the New World. The Dutch forts were eventually traded to England as part of a treaty.