Is the character portrayed as consistently correct when she labels people as mixed-race based on appearance? Because it's not unrealistic for someone to think they're much better at identifying that, or any other characteristic, than they are. And if her colleagues share some of her prejudices, or are just used to her descriptions, her saying "male, 5'9", 160 pounds, brown jacket, mixed race" would be useful in the same way that "male, 5'9", 160 pounds, brown jacket, white" is. And I know they use that sort of description.