I'm confused by your comment, From my reading you seem to say the article suggest squatting but from my reading the article is not advocating for squatting at all. It's advocating for hip hinge where your back remains straight and your hips rotate using your hamstring to pull. Unlike the j-curl you mention the back remains straight. Similar to deadlift technique.
You're right - I went from hip hinge to squat because that's the natural progression of how you would adapt your movement in order to pick up something heavy. The posterior chain is the strongest set of muscles in the body, so the heaviest lifts will involve a squat (which is both a hip hinge and a leg bend, butt drop).
I'm not referring to the standing negative squat as in weight lifting, I'm more referring to the dead life move done by people with longer legs and shorter torsos/arms. You probably know that there are many variations of dead life. What I was referring to, which I took the article to basically be advocating, was a type of bend (lift) that isolated the spine as much as possible. And I was arguing that use of the spine in a bending, flexing way is not inherently bad - it's just that typical modern (sedentary) life allows the core to weaken and reduces flexibility.
Instead of telling people to isolate to avoid injury, we should be telling people to move more (starting lightly) to increase flexibility - then add weight to increase strength everywhere.
