that article is a long winded way of rehashing the old Tzarist claim that the Russian Empire was the inheritor of the Byzantines, a self-styled "Third Rome".
Putin simply sees himself as the new Tzar, and by extension master of the lands of the Third Rome, i.e. the Baltics, Ukraine, et al.
https://brill.com/view/journals/joah/4/1-2/article-p28_4.xml