The median/mean ratio is problematic for correlating race with income disparity, as it gives more weight to the right side of the income distribution than the left (If Bill Gates' income doubles, the median will stay put but the mean rachet up quite a bit. If Joe pool attendant's income is cut in half, the median will again remain the same, but the mean will only drop slightly). The poverty rate is not an optimal variable either, because it involves only a fraction of the income distribution, has contingencies like family size, varies based on age, and doesn't take into account cost-of-living (poverty rates tend higher in places with a lower cost of living because nominal wages are lower, but this doesn't tell us little about wealth disparities).
Robert at the eponymous Robert's Rationale suggested use of the Gini coefficient. It scales between 0 and 1, with 0 being perfect income equality and 1 representing a single person with all the income. This eliminates the problem of affluent pull and captures the entire income distribution.
This slightly moderates the strength of the correlations with the significance factor remaining zero. The r-squared for a higher Gini (more income inequality) and the black/Hispanic grouping is .56. For median/mean, it was .58. For non-Hispanic whites/Asians the correlation of lower Gini (more income equality) falls to .43 from .44. While the change is trivial, using Gini provides greater accuracy.
So how should open-border types react? Progressively, of course. They should not look to ten years in the future like those short-sighted conservatives. Instead, they can take the longview--if we accelerate the underclass immigration rate and white birthrates remain below replenishment, in a century the income gap will begin to narrow as the new arrivals are ever-closer to the national average (because it's been falling for the last ninety years)!