The way I read his words was that certain races/religions/orientations determine how good of a parent they will be.
All other things being equal, a child is better off with a mother and father.
All other things being equal, a child is better off with parents of the same ethnicity
Well, when reading that race, religion, and orientation should be considerations because they certainly are factors that determine how good of a parent someone will be, I didn't really see the link to the next two sentences.
Yeah, all other things equal, it's probably best to put a child with parents of the same ethnicity. It looked like you were claiming that "race, religion, and orientation are factors of how good a parent someone will be."
In other words, it looked like you were making a claim that the quality of someone as a parent is affected, at least in some way, by that person's race, religion, and sexual orientation. In other words, when I read your post it sounded like you were claiming that, all other things being equal, you could determine the quality of someone as a parent by their race/religion/sexual orientation.
I don't disagree that, if everything else is equal, matching people together homogeneously would probably be best. But that's not what I took from your post.