Not sure what the legal system there is. According to the article, the health insurance sets what you may do when on sick leave. Their health insurance apparently even limited the times when they could leave their house. Incredible, this is like jail!
My apologies if this is thread drift - in which case this post will disappear like snow in summer - but in France, if you are on sick leave, the Sécurité Sociale also imposes rules on when you may leave the house during the working day if you are not going to the doctor or the pharmacie, regardless of which industry you are working in or even if you have no employment at all. The German regulations quoted above do not surprise me in the least!