The article itself encourages this, as the authors use the term "determinants" rather than causes but the authors offer up some causal stories; my favorite involves the way Walmart's "Save Money, Live Better" causes people to think like racist protestants, or something like that. That bit is on pages 10-11 if you want to read it; the folks at Atlantic Cities didn't like this bit either.
The other fun bit is the puffing up of the Walmart variable as being the "most statistically significant". Indeed, it has the second largest t-statistic in the final column in their Table 2. What matters, though, to interpreting the results is its substantive significance, not its statistical significance.
My explanation: Walmart is better at predicting where low income whites live - they are (many of) the folks who shop at Walmart so Walmart has some incentive to be good at locating them - and they are also likely the ones who form groups that end up on the Southern Poverty Law Center list - than are the authors, whose remaining covariates do not dispel my concerns about omitted variable bias.