I'm not entirely sure how someone can prevent the publicly available Google Analytics code from getting hijacked. The author is claiming the sites responsible

I'm not entirely sure how someone can prevent the publicly available Google Analytics code from getting hijacked. The author is claiming the sites responsible aren't even going to his site, just using, again, publicly available information (GA JS code and his very public API key). Really, it sounds like the author is claiming that JavaScript only analytics solutions are the problem, not that GA is inherently bad (clickbait title aside). Beyond that, as a few people have stated ITT, most of your GA reports are pure fiction already and it's worse the larger your site is. If a significant fraction of your total data is garbage, you aren't going to get much out of it, even if you can clean it up.