However, stating such a belief is not in and of itself racist, it in no way promotes hate nor advocates racial supremacy, anymore than God does in His words in Deuteronomy and elsewhere.
I still don't see any blacks or other non-white race in Hasidic garb at the Waling Wall. I do see there are black Ethiopian
Jews, however it is apparent the majority of Jews don't recognize them as literal descendants of Abraham.
This is an issue you probably should take up with them, they believe, apparently as Murray does, the descendants of Adam were Caucasian.
Due to these observations, IMO there is no racism involved in making such a statement.