That's very simplistic analysis. The impact of immigration on the wages of native-born workers, even low-skilled ones, is definitely not a settled question [1].
[1] http://blogs.wsj.com/economics/2015/06/01/does-immigration-s...
[1] http://blogs.wsj.com/economics/2015/06/01/does-immigration-s...
The article you've cited addresses immigration in general, not low-skill immigration by itself. This could support argument in favor of a selective immigration policy, not massive immigration of low-skill workers from developing countries.