And, the answer to my question from an Islamist:
"Abd means slave/servant in the Arabic language, the term could refer to a black or white person. However over time alot of Muslims began to us [sic] the term solely for black people irrespective of the person being a slave or not. This is not from Islam, this is the practice of some ignorant Muslims."
The response appears to be a rationalization to me. There are no whites in Muslim majority countries, certainly historically there were not when the Arabic originated; therefore, the Arabic for slave inevitably applies to blacks. In addition, a person is limited by the terms that are available to use and Arabic as a result embeds racism in the predominant term it uses for blacks.