It wasn't about freeing any type of slavery. Slavery wasn't an issue for either the North and the South. They didn't care about slavery. The issues at the table were protecting the union.

Slavery was an add-on for the war. The North didn't care that the South had slaves, that wasn't the reason for the secession and the Civil War.

You honestly think if the North could've figured out a way to benefit from slavery in industrialization that they would've abolished it...no way.