Thug hasn’t changed. Any thing outside what I stated had negative connotations to it. Large Afros are often seen as aggressive and militant. Afro puffs childish. You can pick any historical black hairstyle and there have been negative associations with it.

As for what they should have been teaching him. One educate themselves first. Realize their bias. As for teaching, be yourself. End of day he was a child and it was his hair. Hair is one of the few things children actually have some control of in their lives and they should be allowed to express themselves. My self perception got immeasurably better when the barber kicked my mom out of my haircuts.

And to be fair bias is not a white or black thing. I got it from both sides. One of my teachers great educator helped drive and foster my love of technology. Also once said it’s to bad I didn’t get that good hair from your momma. She didn’t mean anything negative by it. At that time straighter hair was still seen as an overall positive in the black community.

His parents isolating from his culture casually would have had impact. Intentional or not.