Good analysis.
I believe that the North was envious of the advantage the South had with slave labor. The cotton industry was making the South very wealthy after advances in cotton production increased profits. The Cotton Gin was just one of those advances. Soon there would be automation in picking and the South could move their slave labor force into textile production and out-compete the North’s textile industry. The North wanted the slave advantage gone and used moral arguments to get public support.
The first practical cotton harvesting machine did not come about until the 1920s. Southerners were already using slaves in their manufacturing operations. Over many years, before the war started, Southerners tried to start textile manufacturing in the South. Most of these businesses failed, as did most other manufacturing ventures in the South. During the war, the South had to import uniforms for the Confederate Army.