Yeah, that's also the main warning from the blog: the reasoning here is that adjusting how the website code executes on your computer is copyright infringement. The effects of that would go way beyond just adblockers.
I would be interested in how German law works to make this so, IANAL but pretty sure USA copy right law does not work that way. Modification for personal use is normally going to be 100% acceptable under USA copyright law. The DMCA Anti-Circumvention is one exception I know to this but it was and is a big deal for being an exception.
Running any software that then does anything with the same memory space (cheating software or, say, antivirus) is another, separate instance of copyright infringement on top of that.