While I absolutely agree with the idea that every social media has extremes, I completely disagree with the end conclusions.
Other social media services do not actively shape the debate through intense political moderation. There's no "Post tsar" the validates the political health of things that people host.
Sounds like hyperbole to me. Again we can flip this to "twitter is a left wing extremist platform" quite easily by finding the right tweet snapshots and pointing to prior events. And nobody knows the exact algos or moderation mechanisms for any of the platforms, the screenshots you linked say essentially nothing even with whoever that person is narrating. Im not saying hes wrong, but I'm certainly not taking it at face value. On other platforms there are similar reward systems. Blue check-marks for instance, and shadow banning is obviously a thing.
I don't think the argument isn't that other platforms don't have things like "verified" and "shadowbanned". It's the connotations attached to them. On Twitter, just about anyone can get verified. Shadowbanning requires a serious fuck up (for example, Trump was only banned after inciting a riot).
Seems that Parler has taken a very different approach. Attaching political goals and ideology to the business model of a social network.