A few more thoughts:
1. As I recall, Liedloff makes some references to "natural" child care post infancy. Those that I remember were anecdotes from her experiences "studying" H-G and other primitive child care, reporting that children also did not get any special attention from parents, and that parents did not play with children; rather, children appeared eager to quietly hang out with parents while parents went about their daily business. What child needs quality time when he has the opportunity to hang out and learn with beneficient adults at any time of the day?
2. If that other author is claiming nurturing doesn't matter, but then saying that the best way to parent (i.e. nurture) is to mimic paleo parenting, then she is involved in a contradiction. See point 3 below.
3. Which brings me to my last point. Paleo parenting looks like "no nurturing" to some people because it doesn't have what we think of as "nurturing." But it doesn't need what we call nurturing because it is so fundamentally different from what we do; just as paleo eaters didn't need dentists or diabetes treatments because their lives/diets were so fundamentally different.
Just because paleo parenting doesn't have what modern people call nurturing, doesn't mean it isn't nurturing. Natural nurturing isn't pretentious or obvious, but organic and genuine, whereas modern "nurturing" is obvious, pretentious, and mechanical and probably useless or even harmful.
It is similar with learning. Paleo kids don't need school because they are allowed to learn naturally/spontaneously by just hanging out with and mimicking adults and participating in the tribal activities. Our "quality time" and "nurturing" activities and schools are all sad attempts to remedy fundamental dysfunctions, the same way that diabetes drugs are sad attempts to remedy a dysfunctional lifestyle/diet.
This reminds me of a passage from the Tao Te Ching; in the first section try substituting "nurturing" for "integrity":
The person of superior integrity does not insist upon his integrity;
For this reason, he has integrity.
The person of inferior integrity never loses sight of his integrity; For this reason, he lacks integrity.
The person of superior integrity takes no action, nor has he a purpose for acting.
The person of superior humaneness takes action, but has no purpose for acting.
The person of superior righteousness takes action, and has a purpose for acting.
The person of superior etiquette takes action, but others do not respond to him;
Whereupon he rolls up his sleeves and coerces them.
Therefore,
When the Way is lost, afterward comes integrity.
When integrity is lost, afterward comes humaneness.
When humaneness is lost, afterward comes righteousness.
When righteousness is lost, afterward comes etiquette.
Now, Etiquette is the attenuation of trustworthiness, and the source of disorder.
Foreknowledge is but the blossomy ornament of the Way, and the source of ignorance.
For this reason,
The great man resides in substance, not in attenuation.
He resides in fruitful reality, not in blossomy ornament.
Therefore, he rejects one and adopts the other.
In other words, following our "knowledge" we took apart the natural way, created a lifestyle fundamentally at odds with human nature, then when dysfunctions arise, we attempt to fix them by inserting another artifice even further from human nature (like pretentious "quality time" or giving Ritalin to restless children).
That reminds me of another passage from the Tao Te Ching (Ch. 48):
The pursuit of learning leads to daily increase,
Hearing the Way leads to daily decrease.
Decrease and again decrease, until you reach nonaction,
Through nonaction, nothing is left undone.