A debate could ensue is slavery right or wrong. History shows that slavery existed at different times by many different peoples and cultures and races worldwide. Even practiced, and promoted within their own negro race. This does not make it right or wrong, only that it has come & gone throughout the ages.
When it is agreed by a societal majority that slavery is a wrong, and society does not want it then restitution must be made according to modern law practices.
Slavery re-instituted would not be restitution since it only continues to break its own law.
Citizenship is not restitution since it does not return things back to its original state. This only creates more wrongs. In similar fashion of today as example should todays illegal immigrants be rewarded with citizenship? Is that restitution for the wrong? Or is repatriation back to their homeland closer to restitution?
Repatriation back to their native continent africa is the closest solution to restitution to return matters back to the original state before the declared wrong.