Germany's constitution specifically prohibits the taking away of citizenship––it's one of those lessons learnt from the Holocaust when German jews were systematically disenfranchised by taking away their citizenship. Quote:
Article 16
Loss of citizenship may occur only pursuant to a law and, if it occurs against the will of the person affected, only if he does not become stateless as a result.[0]
There is a very narrow exception for certain configurations of dual citizenship, but there's no reason to believe this guy has a second citizenship––his name is more German than comfortable for my tastes, and it would probably be mentioned in the article because it would draw yet another government into this comic relief of an international incident.
Come to think of it, I now kinda wish he had some interesting dual nationality. Cuban, maybe. Or North Korea, if one can dream.
0: https://www.btg-bestellservice.de/pdf/80201000.pdf
