Hi Kai, thank you for your attention to this matter. 
Apart from the fact that this is an account created by a banned user to evade their ban see (https://www.openstreetmap.org/user_blocks/17159), I have tried explaining my issues to the user via DMs in an extensive message, and they simply replied "You're all talk, I'll catch you and f*ck you up." These types of personal menaces do not have their place on OpenStreetMap. But this has already been reported and taken care of by another member of the DWG. All 3 (yes, 3) of that person's accounts have been banned. I am constantly monitoring the area if they create another one.