I don't think that's the reason the guy commented that way.
Some people are prejudice, it doesn't matter what colour they are. Even if they happen to be black, they might assume that everyone that isn't is a racist, they might even attempt to make it sound that way just to make it look like they are victimised so they can claim sympathy.
Those kinds of people are leeches on society, they attempt to utilise a social problem like racism for their own greed, to turn into a quick buck or undermine a person just because they want to feel empowered. These are likely the people the guy refers to.
The problem is that some people are too quick to stereotype, where a couple of people one one ethnicity might do this, the whole ethnicity is suddenly tarred the same. That's where it's incorrect, people obviously have to be dealt with based upon individual merit, one guy does not equal one people. (If that was the case 'a murder' would make every human alive 'murderers')