> It points out that upper-class and middle-class people like to pretend and promote that the nuclear family doesn't matter while themselves acting like it does.

Rich people say you don't need a yacht. Yet, rich people buy yachts. Clearly yachts are very important for becoming and staying rich, and the wealthy are undermining the poor with their "yachts are a luxury" posturing.

It is to be expected that people encountering different circumstances would adopt different behaviors. That well-off people are more likely to live in a nuclear family does not mean living in a nuclear family is the reason they are well-off, nor does it mean that people in worse circumstances would be better off if they made the same choices.