Yes and no. I know Cyprian is very popular in Orthodox apologetics, so you could suggest that it is a defense of Orthodox Ecclesiology, but there are one or two things further down that are incompatible with the Orthodox Faith
(I will confess to never seeing any scholarly articles on the concept of Grace within the Eastern traditions though)
Also if you notice the footnote on Cyprian's use of the title "Pope" you'll find it vague. If I recall correctly he was Bishop of Alexandria which used that title...so I have some questions as to the authors historical knowledge.
"The author of this article doesn't mention the Orthodox Church. But this looks like a defense of Orthodoxy."
Do you really think so? If so, its a rather simplistic one. Even if I hadn't looked at where it came from, I'd have assumed it was from a Protestant source.
Actually the author of this article is not defending Eastern Orthodoxy, he's actually a Reformed (Calvinist) scholar, but I'm sure most EO would agree with his reasons....that patristic Church tradition does not support obesience to one Pope in Rome.