That's enough to qualify someone as such. He is also a German citizen, he is free to claim both/either as he chooses but it's also not wrong for someone to call someone born in a country as being from that country. The wikipedia also cites the only reason they use "German" in his bio is because he responded on Reddit saying he was a naturalized German citizen. Nothing about a demand to exclusively wanting to be referenced as German.
Which by the way, his answer about being a German citizen was because people were attacking him for being born in Russia and claiming Mastodon was Russian spy tools and nonsense like that.
It would only be interesting if the blog writer was asked by Eugen Rochko to replace it with the nationality he prefers to claim, and refuses to do that.