If you attempt to diversify by socioeconomic status (including race), those that are overrepresented be SES and race will appear to be penalized. This is due to the fact that admission to elite colleges is a zero sum game. There are X number of spots. If you somehow diversify to get Z more members of group A then there will be Z less spots to go around.
Not really rocket science.
To me the two big questions really are: 1) Are race and SES the right things to seek diversity, if anything at all? This is oft debated. 2) Is merit the right measuring stick for admission in general? This is rarely debated.