Englishmen who wrote about liberalism during the abolition of slavery made it very clear that it was explicitly about morality.
And industrialization enabled slavery in the US rather than killing it, thanks to the Jevons paradox; the cotton gin allowed for land previously seen as unsuitable for cotton production to be bought up by slaveowners, increasing the demand for slaves (https://www.archives.gov/education/lessons/cotton-gin-patent ; see section "Effects of the Cotton Gin").
I don't recognize your concept of "superexploitation" in the first place.
I wasn't using super exploitation as a specific term, just as intense exploitation.
Slavery was not profitable in the industrial north, just the agrarian south. In the North they used cheap free-labor from Irish and German proles.
If the morality argument holds why did systematic racism not end with abolition?
The fact is that wage labor is cheaper than slave labor. Slavery was no longer required in the Americas, it was a "way of life" for the south, but unnecessary for the country economically. Especially after a global system of trade had established itself, AKA imperialism, and had placed the US into competition with India with cotton and the rest of the Americas with sugar.
My reasoning is that abolitionism only became a widely accepted moral stance BECAUSE it was no longer "necessary" for the Americas' capitalists, but the weapon of racism didn't go anywhere.