The comments that I have seen from him on that topic (and it should be noted that I have only read a small part of his comments so this may not be representative of his thoughts on these matters) implied that those groups were better slaves because they were more resilient or stronger, so were able to better survive slavery than less resilient or weaker groups.
I don't see why that would make people from those groups feel unwelcome. If anything I would expect people from the groups that he says were genetically not as good as slaves to be the ones who would feel unwelcome. The implication is that they are weaker or less resilient.
I don't see why that would make people from those groups feel unwelcome. If anything I would expect people from the groups that he says were genetically not as good as slaves to be the ones who would feel unwelcome. The implication is that they are weaker or less resilient.