Eugene Genovese told a complicated story of American slavery. Perhaps the review is simply suggesting that this book is not up to Genovese's standards?
I would by that except for the fact that this argument is that masters must have treated slaves well because "property!" and Genovese argued the exact opposite: that good treatment came from the feelings of "our family black and white" and paternalism (or even patriarchy). Plus that last line. (I did an earlier version of the comment but it seems to have disappeared.)