For me, the issue is not getting the weight up high enough, but the manipulation of the weight, using your arms, at that height. Seriously, load a ruck or a pack, and then see if it is easier to put it on your back first, then stand, or deadlift it and put it on your back. I would posit that loading the weight on your back and standing up is far safer for your spine than trying to manipulate the pack from your front to your back while standing.
Regarding the size of vertebrae: Why is it that so many traditional cultures have the concept of carrying weight directly on top of the head, or across a yoke, where a barbell typically goes?
He has a point, but I think he's missing/ignoring too much for it to be valid.
*Edit: I may have to review Starting Strength, but I'm pretty sure that shear forces on the spine are higher during deadlifts than with squats. I may be wrong, but I don't think what you said is a valid reason for a healthy person to avoid squats in favor of deadlifts.