All that means is that they can give an equal or even greater preference as long as they don't do it overtly. Or perhaps its better to say that subjective racial preferences are fine (law school), but objective racial preferences (points) are not.
As soon as I saw O'Connor as the author of the first opinion, the result was obvious. So to that extent, it does "make sense". She's wonderful at writing opinions that raise more questions than they answer.