Obviously IMO the proposal isn’t workable, but it’s not so much unskilled take the jobs of skilled. That’s true in the underlying issue as well. The legitimate socio-economic concern about large scale low skilled immigration (illegal or even legal) is how it might it might lower the prospects for low skilled natives in an economic evolution (technology, trade) that’s already hard on them. It’s not the impact of low skilled immigration on high skilled natives.
Maybe it is all about ‘racism’ and just a coincidence that higher educated/skilled people tend to be more comfortable with lots of unskilled immigrants than people further down the scale, all else equal. Or maybe it’s partly based on who faces more competition for jobs and govt services. Populists claim it’s all for that reason, whose ox is being gored. Maybe it’s some of both, along with numerous other things. Such as ‘what does the other side want?’ ‘OK I’m against that and it’s evil’. Or group affinity. It’s not surprising Hispanics have a generally softer view of large scale low skilled immigration that’s mostly (though from all) from Latin America. Even among moderate/conservative type whites, IME Catholics are less likely to be as worked up by Latin American illegals than Protestants of similar socio-econ level, because it’s at least perceived the immigrants are mainly Catholic, though the % isn’t actually that overwhelming anymore even from Latin America.
But yeah, there would be an irony in the inevitable defense of the proposed program that ‘Americans don’t want those jobs’, building the wall, when the wall is being built in part because ‘Americans don’t want those jobs’ is rejected as a reason to have lots of unskilled immigrants.