He means that, statistically, based on studies done, children face more danger from a mother’s boyfriend or mother’s new husband, as compared to a child’s biological father.
This seems to be conventional wisdom. Yes there are fine stepfathers, of course. But the fact that there are fine stepfathers doesn’t negate the point he’s trying to make.
There are fine single mothers, but single motherhood is not an ideal situation or recommended.
There are many wonderful moral peaceful black young men, but that doesn’t negate the fact that disproportionate numbers of young black men are in youth gangs, doing God knows what.