After reading what was written here, I went back to look at what Bennett said. I would hazard a guess that Bennett probably didn't mean for it to sound the way it did, it was just a horribly inappropriate argument. However, I would guess that there is some underlying racism there.
Statistically speaking, his argument would be better if he never brought up race at all. If you believe Freakonomics, just forcing the poorest 25% to have abortions would have a bigger impact on crime. But for some reason Bennett felt the need to bring race into it.
However, there is also an even worse way of reading it. First Bennett said that he thinks the book is wrong. And then he said he knows that aborting all black babies would reduce crime. Read that way, he is literally saying that blacks are more likely to be criminals, no matter their income or social status. While I doubt that is what Bennett had in mind, it would be one way of reading what he said.
Jay