Racism from a passenger and no assistance from crew

My brother and his wife and their 3 year old son were on a flight to Newcastle when my sister in law was putting her book away on the seat pocket in front of her and was abused by a woman sitting in front of her abusing my 3 year old nephew accusing him of kicking the seat and by seeing the colour of my nephew proceeded to call my sister in law a “black bitch” (my sister in law is Caucasian). The crew were called over and advised of what had happened and they actually told my brother and sister in law that they would eject them off the plane if they didn’t calm down. How is encouraging a racist person the answer? Upon exiting the passengers were apologising and not one crew member acknowledged or apologised for what my brother and sister in law had to experience. I am disgusted.