Suppose the following scenario. A person is in line at a store. Let's call them "subject 1." In front of them in line is another person. Let's call them "subject 2." Along comes a third person who approaches subject 2. We'll call them "subject 3." Subject 3 starts calling subject 2 a number of racial pejoratives, then tells subject 2 to "move" and cuts in front of subject 2 in line. Subject 1 meanwhile does nothing and thinks to himself/herself "not my problem."
Subject 2 is a victim of racism. Subject 3 is a racist. But, what is subject 1? They are not a racist by definition. They aren't refusing to stick up for subject 2 out of fear. Subject 1 just doesn't care either way. I'm looking for the right word to describe the implicit lack of empathy for subject 2.