STEM is already very diverse, just look at the engineering or physics departments of any major university. South Asians, East Asians, South and East Europeans, Jews and even Muslims are represented in great numbers.
Only it doesn’t include blacks. So in our twisted political atmosphere of today, it means its not “diverse.”
For some reason it doesn’t seem “cool” for a modern African-American person to be a mathematician, a scientist, even a computer scientist.
I don’t know why. I have known African-Americans in engineering and they do a very, very decent job.