>>520795260 (OP)
He explained this very succinctly. He admires Stalin because he was a great man who rose from being the member of a minority at the edge of the Russian empire, a pariah even among fellow Communists, to being a leader of one of the world's greatest powers. Nick is an elitist and by extension is a strong proponent of great man theory. It's possible to acknowledge that a man could be terrible while also doing great things.
A further point of illumination on Nick's character that you can glean from his admiration for Stalin is that unlike many right-wing types today who are proponents of a society or lifestyle which is rural, agrarian, and pastorally idyllic, (the trad lifestyle,) Nick is very much like an old-school progressive in that his own interests and ideals emphasize and champion urbanization, technological development, modernization, expansion, centralization, and material progress overall. Stalin's industrialization of Russia, brutal as it was, speaks to Nick's worldview in a particular way that the lives of other leaders don't.