This is such bullshit. A 14 year old is using those kind of words because of their parents/family, who their friends happen to be, and what type of neighborhood they happen live in. All of which are outside of their control. Even in high school, kids are not able to make decisions about what kind of person they are or how they feel about very difficult political positions. In addition to generally not knowing what they think about anything, they are also impulsive. That's why they are kids.
The whole "I never had a hateful bone in my body" thing is just so silly. If your parents said racist stuff all the time, and your friends said racist stuff all the time, you would have grown up saying stupid racist shit too - whether you believed any of it or not. Maybe as you got older and saw more of the world, you would turn away from that, or maybe you wouldn't. But I am not going to put that on a 14 year old.