Suppose a black man is walking down the street when a truck pulls up along side him. Three white men get out of the truck and attack him, calling him a "******". This would be a hate crime because the racial identity of the victim is the sole motivation for the commission of the crime.
Now suppose a black man is walking down the street when a truck pulls up along side him. Three white men get out of the truck and attempt to rob him. The black man fights back and one of the men calls him a "******". This would not be a hate crime because the racial identity of the victim is incidental to the commission of the crime. The sole motivation for the commission of this crime is robbery. In this instance, the man is called a "******" because he happens to be black. Had he been overweight, he would have been called a "fat ass," had beeen a woman, he would have been called a "*****," and so on.
Which brings us to the topic at hand. There is no doubt that race was a component of this crime but it was not the motivation of this crime. Had the girls been black or puerto rican or chinese, they would have still been beaten up. Therefore, it is not a hate crime.