This is not a safe practice but it's cool, I don't know how serious the crypto regulation is in Germany or if there is any at all, if there is no form of hate on Bitcoin in Germany
Crypto is legal in Germany, which means they are crypto-friendly, and as such, there is regulation that is imposed on them, but that doesn't guarantee that the creator is safe, because advising on open space have a different kind of regulation most especially on private/public properties.
Based on my belief, the creator of this has two chances: either he or she gets sued if people eventually know the creator or becomes very famous for such an idea.
The creator is already anonymously becoming famous, and every crypto believer loves the idea.