You seem to be fairly knowledgeable about the suspect, I'm just writing aloud as it were.

I got ya.

Statistically, certain races currently have, on average, higher IQs than others. That doesn't mean mean there aren't smart and stupid people in every race, just that the distributions vary between groups. Since we know different races have completely different standards of living, and we know things like malnutrition and poverty have a huge effect on IQ, the IQ disparities could be completely environmental. So while different races do generally have lower IQs than others, we can't say their race is inherently dumber: we can't say it's genetic. Some people do think the IQ gap is at least somewhat biological, but they tend to be white supremacists using it to justify inequality, which is why this topic is so controversial.

As for the India/US/UK variance:

The US limits immigration from a lowish IQ country like India, so that only highly educated Indians are allowed in. You're going to get a heavy bias for unusually high IQ Indians, since you have to be so exceptionally smart to make it in the ultra-competitive Indian education system. The Indians in your country will have extremely high IQs, but that says nothing about the IQ distribution of Indians in general, since you've handpicked them with that bias.

Compare that to the UK, where they just wanted factory/mill workers in the 60/70s: you're not going to get the same bias for high-IQ immigrants. Still, since the living standards are so much better in the UK, the IQ is going to raise in the 2nd and 3rd generations (as is height, bone health, life expectancy etc.) to the point where it's now much higher than the Indian average.

So yeah, race is correlated with IQ, but race prolly ain't the cause. Inequality likely is. Especially given that race, as we see it, is a social construct (eg. Sub-Saharan Africans are insanely diverse genetically, but they're all lumped into the "black race" because they have dark skin).