The whole extension is all about “let’s see when customers go to competition and try to bring them back.” That’s rather shady but it’s exactly the advertised functionality. And I’ve already got the first comment on the blog essentially saying “I don’t care what else they do, this extension gives great suggestions and I love that.” :-)

Yes, but that part is with user consent, so it's an attack on Google and their partners, not an attack on the user.