Taleb's argument is two fold>IQ is morally bad as an idea as it leads to people acting badly>IQ does not reflect reality and has no explanatory power
In the first argument, he misunderstands the point of the Bell Curve, and essentially says that IQ existing will lead to Gattaca. This is wrong, Gattaca is a result of people NOT listening to the Bell Curve and NOT taking IQ into account. The Bell Curve argues that if we don't take IQ into account, we'll end up with a dystopian hellhole with a high-IQ caste dominating a low-IQ caste, and the low-IQ caste will suffer because of the illusions of "meritocracy". Not good enough? It's because you're inherently immoral vermin.
The second argument is just flat out wrong. You can read the "paper" he made on this, or watch his video, or go check out his medium article. He just mumbles about IQ not being "linear", that it involves "eigenvectors" and that you'll "need new math". This is completely meaningless according to every usage of "linear". Non-linear measures are used all the time, and can easily be linearized. He's arguing that because pH is calculated on a log scale, that we shouldn't use it, because even if we couldn't do certain statistical calculations on IQ, and there are none that we can't do on it so it's really a moot point, we would just only use it for certain things and not others. It's a totally incoherent non-argument. It also totally ignores the mountains of evidence demonstrating that no, IQ has fantastic predictive power.
He's trying to distance himself from his Right Wing fanbase so he can still get paid fat stacks to give talks at Harvard.