It's relevant if we assume it's america, because the white suburban middle-class american assumption is that all poor black people will murder and kill you and have no human decency. When of course, the truth is most folks in these places are decent and the crime is minority of the residents who are in gangs and other organized activities.

And trust me, tons of these people exist. I meet live in a city full of folks who claim to be liberal progressives but are utterly terrified to be in the same restaurant as anyone black. The racism is really really deep here, esp among those who claim they aren't racist because they watched Get Out and read White Fragility, so they can't possibly be racist!

But people are dumb monkeys and fear is one of our most powerful/driving emotions, to the point it's the an amazing tactic for fueling brain-rot political takes and policies based in 'black people are all bad people' nonsense. And also, more lately, latino immigrants from south america whose skin color has any significant melanin.

The fact he was white and they were black is only relevant because [their target audience] is expected to relate to the boy’s fear of black people.

Yes, it's used as a bait-and-switch.