You might be right. The Chinese would be a lot more ruthless that our norm, anyways - Probably somewhere along the line of the Belgian Congo. So they’d be able to control more area with fewer people.
In any case, Chinese control of Africa could only improve Africa.
No, they would be ruthless in a different way. As I keep saying, China needs Africa's resources, particularly mineral resources. China does not need the Africans.
China would view the Africans' continued existence in mineral-rich territory as a threat to China's long-term control of the territory. By whatever means necessary, the Chinese would desire the removal of the Africans from areas of strategic value (mining territories, ports, the land that links the two) and their replacement with Chinese settlers.