-Other models of intelligence as wrong and g is real because tests results correlate with each other, which is completely orthogonal to Shalizi's point. Because of the very nature of testing the results are going to correlate with each other; the most trivial example is, using Taleb's example, if dead people take the test. Dead people are dead and have an IQ of zero, and this is enough to increase the correlation (https://twitter.com/nntaleb/status/1114977580053147648).
-Apparently confirmatory factor analysis means g is relevant because...confirmatory factor analysis means g is relevant? Nothing addresses the fact that g could be an artifact that arises in any set of measures that correlate with each other regardless of the origin. Adding to that, there is scant evidence of any link between g and the underlying neurobiology and/or actual causal genetic mechanisms, beyond very trivial cases such as obvious malformations etc. On the contrary, neurological findings are pointing to the opposite direction (https://www.ncbi.nlm.nih.gov/pubmed/23259956).
-Even if we have no idea how g works it's still useful for predictions for stuff like educational attainment so it's relevant. Well duh, if you're good at taking tests you're going to do well in an environment where your attainment depends on your doing well in tests. Again, there is enormous circularity in reasoning. And as for the other outcomes, look at it this way: you could combine many measurements from your body (say, various analyzes from blood samples, but even trivial things like number of legs or amount of blood in your body could do), find they all correlate with each other (because when your body is breaking down it is likely damage to one organ that's spreading damage to other organs etc.), and from all that stuff you could draw a general "health quotient", or HQ. It would be highly heritable, there would be literal millions of SNPs that are associated with it. It would have immense predictive value for a variety of social outcomes. Does this mean that HQ reflects a unidimensional, physical reality in your body? Does this mean medical practitioners would have any use of it? And more crucially, does this mean that attempting to optimize for it (as opposed to, you know, optimize for actual real things that we can readily see) wouldn't be an utterly fruitless endeavor?
One last thing, since people seem to love brandishing GWASes around like a magic wand: people in the community are becoming increasingly disillusioned with them these days. (The head of EMBO, Ewan Birney, recently spoke about this. Note that I'm talking about academic geneticists, not the small clique of psychologists/"independents" from institutes with shady funding whose names invariably pop up when dealing with the less savory elements of the debate.) Again, for a geneticist, you need to find an actual genetic mechanism to prove something is "genetic", otherwise you end up with ludicrous associations (https://twitter.com/SbotGwa/status/1151964472921219073, or a GWAS for type of fat used in cooking). This has not deterred people from less rigorous fields such as psychology to attempt to GWAS for literally anything. A charitable interpretation is that people conducting such studies are unusually naive, a less charitable one would be to draw connections among the aforementioned small clique and correlate them with the views people in said clique have expressed, and reasonably infer that a motivated agenda might be at play here.
Of course I'm not looking to convince you since you appear to have read a truly gigantic amount on the subject and probably have a list of well-prepared rebuttals for literally any argument so that anyone with less time for online posting would never have the last word, so this is more of a post for any passer-by who'd think that IQ has any relevance beyond some niches of psychology. It's certainly not a thing in mainstream popgen or any field of genomics and if someone presented an abstract at any conference dealing with the kind of stuff posted on humanvarieties they'd be laughed out of the room.