His entire point is that, while IQ may identify good, obedient candidates for BS jobs, it is not broadly applicable as anything like a general metric for life.
His first sentence in linked article starts with: '“IQ” is a stale test meant to measure mental capacity but in fact mostly measures extreme unintelligence'. Why would any developed country want hordes of "extremely unintelligent" immigrants?
Which is why there exist countries with extremely harsh immigration policies that are first-order eugenic. Singapore is one of them.
[1] There are many studies that report similar values, https://www.sciencedirect.com/science/article/pii/S016028960...
[2] Anecdotal but informative: https://undark.org/article/in-south-africa-decolonizing-math...