The Importance of IQ Tests

Dwarkesh Patel published an article called "Contra David Deutsch on AI". This article was actually a defense of IQ theory against the charge (often made by fans of David Deutsch) that the existence of Explanatory Universality destroys IQ theory entirely. But how accurately does Dwarkesh portray Deutsch's view? (For that matter, how accurately do fans of David Deutsch portray Deutsch's viewpoint?) And how good are Patel's criticisms of Deutsch's view? 

With some help from a tweet from Brett Hall on IQ theory, we compare and contrast Patel's and Hall's viewpoints and lay out the disagreements that exist. 

Brett argues that Explanatory Universality implies we are all equally intelligent (i.e. have an equal capacity to learn) and that the only difference between people is our levels of interest in the knowledge that currently society happens to value. Is he correct? Or are the experiments cited by Patel wrong? If so, how?

Or to put this another way, if we did demonstrate via an experiment that some people do gain knowledge faster than others (as Patel claims), would that refute the theory of explanatory universality? Or are Brett's claims not actually implications of explanatory universality?