How is that a straw man?

You first have to prove that X is equal to Y. If intelligence is not equal to IQ scores then you have no argument. (Perhaps not necessarily equal. Nearly equal would be good enough. 1% accurate might even be useful, but there is a lot of controversy about how accurate IQ scores are.)

Conflating Y with X is a straw man.

IQ scores are the best [or only] measure, [therefore they are an accurate measure.]

That's another fallacy. Imagine you have a telescope capable of giving the chance of alien life in a visible galaxy. The telescope gives readings, 2%, 5%, 20%, 1%, 0.00001%, etc. However, you actually have no idea if that galaxy contains alien life. You might go to the 100% galaxy then find nothing. You might go to the 0% galaxy and find an abundance of life.

Humans have no accurate measure of human intelligence. They can't even make a drone as nimble or smart as a bee using materials a hundred times the size. Humans don't even understand what sleeping does--don't even pretend there is a magic number to estimate intelligence.