Northern states were given no special protection or largess by the tariffs. Exactly the same was available to any southerner who decided to start a factory and actually make something. Southerners chose not to do so.
Your whole argument strikes me as much like those today who claim that minorities who choose not to study hard and therefore earn less are being disrciminated against.
BTW, I've been looking for some time for the records of the 1860 Congressional election. What would have been the party breakdown in Congress if the South had not seceded?
My expectation is that it was such that opponents of Republicans, all southerners and northern Democrats, would have held a significant majority, making it impossible for the Republicans to vote in the Morill tariff. If I understand correctly, they were unable to pass it as it was until a lot of southern representatives left when their states seceded.
Lincoln could not have done anything to the South against an anti-Republican majority in Congress.
Yep all they had to do was buy the machinery from Northerners, or import it and pay huge tarrifs.
As for choosing not to, that was not the case. The south was industrializing, Atlanta was a railroad hub (and was later burned). Iron furnaces and foundaries existed, and it was only a matter of time until the South became self-sufficient. With that self-sufficiency would come a sharp reduction in tarrif revenue as the South imported less.
By destroying as much industry as possible, invading armies set back Southern Manufacturing development significantly.