First off, Anthony Johnson was one of the first ever BLACK slave owners, not first ever slave owners. He was originally a slave himself. Secondly, maybe you've never heard of this before, but native Africans are often racist towards African Americans. Not a clear comparison here, but it goes to show that people can be racist against their own race.
Regardless, nice strawman argument you created. None of this has anything to do with the fact Sterling doesn't mind his gf sleeping with black men, but will get upset if she is seen on Instagram or at his games with one. He doesn't want his peers making fun of him for dating someone who associates with "those people." Considering his history of discrimination against minorities, what exactly is your point here?