Wow, the author is not exaggerating when saying it is a scam. Looking at the .feedback page for Stack Overflow, it says at the top, in fairly large letters "We make Stack Overflow, where the world's developers get answers, share knowledge & find jobs they love. Also proud builders of the @stackexchange Q&A network." Then at the absolute bottom, in small, washed out print it says "Disclaimer: This site is provided to…
It is a scam, but the reality is nobody will ever go to these domains, they will never be ranked in google or bing. So who cares. I could create a site called myfeedbacksite.com/google or google.myfeedbacksite.com.. same thing.
Also, the domains you suggested are quite different from the current situation. A site like myfeedbacksite.com/google is clearly not owned or operated by Google. Very few people would be confused. Whereas a site named google.feedback is far more confusing. Not sure anyone would know if it's an official Google site or not.