Reddit reviews Emancipating Slaves, Enslaving Free Men: A History of the American Civil War

I don't think that is quite fair. While an unfortunate number of libertarians (I would be sure to add DiLorenzo to your list) write terribly inaccurate "histories" of the Civil War and Lincoln, there are also a good number of scholarly libertarians who contribute serious analysis and original research to the literature on the war. For instance, Phil Magness is a vocal libertarian and his Colonization After Emancipation was an important contribution to Lincoln studies when it came out in 2011. Similarly, Jeffrey Rogers Hummel, quite a radical libertarian, wrote Emancipating Slaves, Enslaving Free Men and the forthcoming Deadweight Loss and the American Civil War: The Political Economy of Slavery, Secession, and Emancipation, which both showcase rigorous analysis and an erudite understanding and appreciation of the literature. John Majewski, too, is a libertarian and his Modernizing a Slave Economy was quite well-received.

In short, I think it is politically-motivated publications that should be suspect, not works by libertarians per se.