Given that not even Taleb disputes IQ effectiveness on the left-end of the spectrum, meaning the low end, letting waves of refugees in from sub-saharan Africa (average IQ below 70 [1][2]) would definitely be a net loss for a first-world country.
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...