If they expressed a belief that people of other races were inherently racist, then that would be a negative stereotype of that race and would be racist.

But no such belief was expressed in the article. They only said "No one was listening to us, and I can’t prove it, but I really feel in my heart: if Jahi was a little white girl, I feel we would have gotten a little more help and attention."

There's nothing in that statement expressing a view that the hospital staff was inherently racist because of the hospital staff's race.