I agree it's a glaring oversight, but I don't think it's a supply/demand effect so much as a demographic shift: I'd bet that the group of American working men ages 30-45 without a high school diploma now tilts much more heavily first-generation immigrant than it did in 1990. The percentage of native born Americans with high school diplomas has risen pretty consistently over that period, and immigrants as a % of the population has been spiking since 1970, rising from 8% to 13% from 1990-2013.[1]

As the Census Bureau pointed out in 2003:

The percentage of the foreign born with a high school diploma (67 percent) was dramatically lower than that of the native population (88 percent), but paradoxically, the percentage with a bachelor's degree was the same (27 percent).[2]

I don't think it's outrageous to suggest that first generation immigrants may have less remunerative employment opportunities than native born citizens, regardless of their education level, but particularly without a high school diploma.

[1] http://www.migrationpolicy.org/programs/data-hub/charts/immi...

[2] http://en.wikipedia.org/wiki/Educational_attainment_in_the_U...