I hope I convey a lack of snark in this question, RJ:
Do you think the name would have as visceral a reaction for you if your Grandmother had not taken the time to correct you?
You shared your experience with the strong reaction your Grandmother had to your youthful experimentation with the word. I would imagine that experience would be formative. I am picturing that in a similar vein many African American Grandmothers have rebuked their offspring for using the "N' word, regardless of its intended usage or connotation.
I am re-thinking my stance on it a bit when I read that the term came from the color of the underside of scalps, rather than what I had always assumed that it referred to a sun-baked ruddy complexion.
The term didn't come from the color of the underside of scalps. The underside of a white scalp is just as red.