Correct me if I'm wrong, but doesn't the content maker get to decide if they in fact do want all the AMP benefits or not? If I remember correctly you can choose to disable the whole AMP cache google link, and only use the AMP optimizations.
Secondly, He goes on for a few paragraph at the start about how anyone can do this, but that's not so true is it? The whole point of the AMP redirect is that it's on Google cache servers, and unless you have a lot of money, that ain't gonna be cheap.
So at the end of the day, the last part is optional, and it's basically you paying for the cache with allowing them to use their domain (will all ads and traffic stats still sent to you).