The reference to Constantine in the Divine Comedy is about the legend in which the emperor, leprous, recovered thanks to the baptism, and then the authority of Rome moved to the so-called city of Constantine (Constantinople).
"Per ceder al pastor si fece greco" (Paradise, XX, 57). Surrendering to the shepherd, he turned Greek.
By the way, in my opinion all the polemics between Reghini and Evola, apart from the deep Masonic trend of the first, originated mostly by the fact that the later chose to title his book just 'Imperialismo Pagano', the same of the article by Reghini in course of translation here. Afterwards, Evola justified himself saying ironically that Tradition and relative terms have no copyright.