Not sure exactly what kinds of comments you're looking for here, but I hadn't heard of this paper before your post. Having looked through it, I'm pretty skeptical overall. Here is a link for anyone who wants to read it.

The author uses voting pattern data and a number of economics-based assumptions (e.g. people vote based on their interests, therefore people with an economic stake in the war would vote to protect their economic interest) to extrapolate voter intent based on their chosen vote. Using quantitative methods, he analyzes exactly how much voting patterns changed among Americans employed in manufacturing sectors (5-6% of the population, per his own data), finding a shift in favor of Republicans between the 1860 and 1864 election. Due to slim margins of victory for Lincoln in several states, this shift was enough to secure as many as 65 electoral votes for him in the 1864 election, though the author himself notes that these electoral votes could not have altered the outcome.

Then, accounting for various alternate explanations that might have challenged his argument, he makes the following conclusion (emphasis mine):

I have argued that an approximately 2.25 percentage point shift in voting for Republicans between 1860 and 1864 is attributable to the economic interests of manufacturing, a factor pivotal in states accounting for over a quarter of electoral votes. Causes other than a desire to keep the South in the Union seem unable to explain this shift, suggesting that a concern for keeping the South as part of the Union motivated this 2.25% of voters. If 2.25% of voters were on the margin between voting for the Democrats and Republicans and changed their votes to keep the South in the Union, then the actual fraction of the population with these economic interests was likely much larger, since many with this interest either kept voting Republican or were motivated enough by other concerns to keep voting Democratic. Thus, given that Lincoln could not have taken any action that did not reflect the will of at least a substantial part of the population, this paper offers strong evidence that economic motivations were one important component in the North’s decision to fight the South after it seceded. More broadly, this paper is a case study on why states tend to try to fight secessionist movements, even in democracies where leaders are less able to extract rents from seceding regions. These results suggest that powerful groups may benefit economically from having a union and that their influence may encourage countries to resist secession, even of relatively poor regions like the U.S. South.

In other words, he claims that this small shift in manufacturing voting patterns must invariably reflect a much larger tendency of Northerners to vote according to similar economic interests.

Here's why I don't buy it:

• The assumption that manufacturing voting patterns must necessarily reflect much broader voting patterns is one hell of an assumption, and one which the author does not really justify. The paper specifically examines voters in the manufacturing sector without really differentiating that population (worker vs. owner, for instance). That population, as acknowledged, was quite small, but it was also unevenly distributed and seems to implicitly play into an old caricature of an industrialized North which bore little resemblance to the agricultural South. In fact the North was out-farming the South when the war began (though not cotton, and of course not using slaves). About half of Northerners were not farmers, but that didn't make them factory workers, either.

• His working definition of "economic interest" seems incredibly narrow. Slavery was an economic institution (as well as racial, social, cultural, etc) with strong capitalist ties, but economic interests for/against slavery cannot be painted with a broad brush. This author makes no mention of free labor ideology or competition over the West in his economic conception of the U.S. during this period, and uses Eric Foner's pivotal book on the subject to make a passing reference regarding tariff policy (!!!). That tells me he picked up the book, read it very selectively, and only used the bits that fit his hypothesis.

• This guy apparently missed the cultural turn. Much of his historiography is outdated despite publishing in 2012, and he seems unaware that historians don't tend to rely on quantitative methods alone anymore. Read through his brief section on prevalent historical interpretations of Civil War causation and it becomes clear quickly that he didn't really investigate that. If he's going to argue for economic interpretations of the conflict he should be more aware of what historians think about that topic currently, as well as embrace conceptualizations of slavery as an economic system! If he wanted to make a smaller argument about voting patterns in the manufacturing sector, this stuff would be less necessary. But if he wants to make sweeping arguments, it's kind of a big deal.