There's a huge difference between the facial recognition issue and the result sorting issue. The former case is some kind of computer algorithm causing upset among a certain group, threatening their brand and marketing, therefore encouraging Google to manipulate it to satisfy their customers. The latter is a computer algorithm behaving as it always had, Google then manipulating it for "reasons unknown", resulting in a brief scandal, and then further manipulation by Google to ensure fair play.
The reason I'm asking for the market purpose is because it's relevant to prove your theory applicable to this instance. If you start from the POV that corporations ONLY do things to react to popular opinion, then obviously you're right by definition, but I'm disputing that theory. Corporations react to popular opinion when they feel it will make them sell more product; if it can't be demonstrated that displaying "hillary clinton indictment" would impact their sales, then there is no clear economic motive behind the action, and therefore it becomes a question of why a corporation would go out of their way to voluntarily spend effort on work of no value. Since the move was controversial and immediately caused Google to react, and since this is a corporation that invented the PageRank algorithm in the first place, the move could arguably even be viewed as creating negative publicity for them. I mean, I'm right-wing as fuck and I don't care that popular left-wing searches are displayed; I fully expect them to be as someone that uses Google for its ability to provide relevant and important results. I don't think most people that lean (D) are going to have conniptions just seeing "hillary clinton indictment" pop up, and I've never read any case where users had complained about said search term. Therefore, since the profit-motive seems negligible at best, I propose that this is an exception to your argument, and that when corporations are still controlled by their founders with a tight leash, their founders are likely and able to inject personal biases.