I think you have to ask yourself the fundamental question. How does John make a living? Perhaps he could move to a paid subscription model. That seems fraught with risk but it's true it's a possibility. But even then you pander to your paid audience vs the paid advertiser (if all your paid subscribers are Apple fans and you noticed a 10% subscription cancellation when you belittle the Apple Watch what happens to your behavior?)
The next alternative is he relies on advertising. When there is a conflict of interest in advertising it's mostly around transparency (the site does legitimate and paid product and service reviews side by side and so you don't know what is paid content and what isn't) This approach though seems very transparent. The worse case scenario is a product or service he advertises becomes crappy (based on his backlog he wouldn't need to accept an upfront crappy product) and he doesn't allow them to sponsor again. The biggest crime is he holds off calling out said crappy product because at one time he took money from them. I'm not sure he'd do that and that would only be a real issue if JG was the sole or primary source of reviews for the service vs all the other channels that review products and give you a wide range of opinions to draw on if you need them.
TL;DR: All commercial models involving information sharing are flawed so you have to deal in shades of gray and this seems good to me.
Traditional journalism doesn't try and mix advertising and content to the level this does. This feels closer to BuzzFeed's infamous organic content (http://techcrunch.com/2014/08/12/buzzhome/) than it does to what a newspaper might do.
That's very traditional. Most computer magazines f.e. are under so much pressure that a complete separation is difficult.
Even the ones that still have a separation, are a little bit more gray in the sense, that they do special deals i.e. free software for their coverstory and so forth.
You could buy a shirt and it came with the membership, or pay less for just the RSS membership. He delivered a personal RSS link with a random string. That worked until people moved to Bloglines, because it shared URLs among all its users and thus exposed private URLs to anyone looking for the daringfireball.com feed. At that point, he moved to password protected feeds, until people moved to Google News, which didn't support password protected feeds. This is when he began the weekly sponsorship model.
The next alternative is he relies on advertising. When there is a conflict of interest in advertising it's mostly around transparency (the site does legitimate and paid product and service reviews side by side and so you don't know what is paid content and what isn't) This approach though seems very transparent. The worse case scenario is a product or service he advertises becomes crappy (based on his backlog he wouldn't need to accept an upfront crappy product) and he doesn't allow them to sponsor again. The biggest crime is he holds off calling out said crappy product because at one time he took money from them. I'm not sure he'd do that and that would only be a real issue if JG was the sole or primary source of reviews for the service vs all the other channels that review products and give you a wide range of opinions to draw on if you need them.
TL;DR: All commercial models involving information sharing are flawed so you have to deal in shades of gray and this seems good to me.