It feels like there's two possible explanations here. One is that somehow the website has been incorrectly flagged or blacklisted, like the example he mentions with Bing. In that case, it seems like it'd be at least nice for Google to be able to look into it, but it also might be the sort of thing where Google just decides it's not worth the effort.
The other possibility is that Google just updated their search algorithm in a way that happens to not like this website as much as it used to. Not because anything is wrong with it or because of any bug in the algorithm, just it now prefers different attributes, and that changes where this site ranks. If this is the case, there's really nothing to be done. There's no ground truth result ranking for any particular query - if Google feels its new results are better, that's their business.
If your entire business depends on an arbitrary algorithm preferring your website over other very similar ones, and you will lose everything if that arbitrary algorithm happens to change, eventually it's going to happen. It sucks, and it's maybe unfair in a cosmic sense, but there's really nothing to be done.
There's definitely a large set of sites that should not have a viable choice, not from Google and not from anyone else, as we-the-users want our distribution channels to filter out various groups of SEO spam.
The only question is whether this site is one of these or not - and even if it's not, a certain number of 'false positives' is acceptable and less strict filters definitely are not. If you're running a site that's skirting the line between spam and not-spam, then either you take on the risk that you might be dropped by google and others, or (perhaps preferably) stop doing that thing and do something substantially different.
The point I'm making is that if his business is only possible because of Google, it's silly to ask what his alternatives are.
It's not like he'd have a thriving business if only Google didn't exist. Instead, he's reliant on Google choosing to rank his page highly enough to get traffic for search queries that will result in people clicking on his affiliate links (who he's also reliant on). Google doesn't owe him any particular ranking. If people search for his example "cheap portable generator", does Google have some ethical responsibility to put his site at the top? Or even on the first page? Or to never change where they rank it once it reaches the first page?
What does that have to do with it? If other search engines were more popular, would that change this situation? Maybe there'd be a handful of algorithms to arbitrarily rank him instead of just one, but the dynamic would still be the same. He'd still only be in business as long as their algorithms happened to think his website was slightly more relevant for "cheap portable generators" than other websites.
> There's no ground truth result ranking for any particular query - if Google feels its new results are better, that's their business.
That's a real issue - there is no rigorous and systematic monitoring of Google's results. There could be horrible biases and we don't measure, don't hold them accountable. There has been a recent spat at the Google AI Ethics department where a researcher accused Google of being biased because it uses language models trained on biased internet text (thinks doctors are men and nurses are women). I'd say - before going so deep, first check the actual page results for bias, it's 1000x easier to do that and gives much more useful results.
The other possibility is that Google just updated their search algorithm in a way that happens to not like this website as much as it used to. Not because anything is wrong with it or because of any bug in the algorithm, just it now prefers different attributes, and that changes where this site ranks. If this is the case, there's really nothing to be done. There's no ground truth result ranking for any particular query - if Google feels its new results are better, that's their business.
If your entire business depends on an arbitrary algorithm preferring your website over other very similar ones, and you will lose everything if that arbitrary algorithm happens to change, eventually it's going to happen. It sucks, and it's maybe unfair in a cosmic sense, but there's really nothing to be done.