I am a former Yelp engineer. I think the thing this story describes is dumb and bad and they should stop doing it. Inserting yourself as a useless middleman is a classic shitty startup move.
Here are some great reasons for current and former Yelp engineers not to engage in internet debates about accusations of nefariousness in other areas such as the review filter or sorting algorithm:
1. Being in internet debates mostly sucks in general, especially with people who by default hate you.
2. Yelp has a blanket policy that you shouldn't engage in these debates.
3. Yelp has been sued some number of times and might be again. I would be paranoid that something I said here would be used in another bullshit lawsuit, especially if I were truly in a position to know things.
4. It's pretty clear that the PR battle was lost long ago, regardless of the truth. Leaving a comment on a thread like this changes literally nothing and is a waste of time. Yes, that means I think I'm wasting my time right now. :-)
Every Yelp engineer I've met has intentions at least as good as, say, the average Google engineer. Sites like Yelp can have negative effects on small businesses the same way e.g. Spotify might have an effect on independent music or Airbnb has an effect on the apartment rental market in a city, and engineers aren't always good at recognizing those effects as problematic, but Yelp engineers are certainly no worse than your standard Silicon Valley type.
I still trust Yelp reviews more than I trust local business reviews on any other platform.