Earlier quoted context omitted.
I think moderation should be about the words that are being said, not the ideas that are being discussed. A free speech platform should allow a wide range of topics, but it's not expected to stand for all manner of trolling and bad faith argumentation. I think that conflating the two is tripping a lot of people up in the debate about the topic.
In the end you end up with the same problem. All the "exterminate the jews" types go to the free speech platforms at which point everyone else leaves, even if the people with the ideas that aren't liked are using respectful language. It's not just the bad faith and trolling that make people want to leave the site, it's the base level ideas of the people who have been moderated off other platforms.
Not every platform needs to have _all_ the users. I know that it's a bit of an anathema on a discussion board built by venture capitalists to say that the goal of a social platform should not be to maximize the amount of users and engagement, but here we are. I think optimizing your service for "everyone" is a bad strategy in competing with existing social networks, especially coming from an "indie" background. Not that Parler is exactly indie.
[1] I'm saying this as someone that is working towards a discussion platform that targets smallish to medium communities formed around a common interest. In this world if moms wanting to share their latest knitting project are excluded from a service that targets free speech people, that's fine, there can be a knitting community out there also for them. Having these two communities intermingle by using something like ActivityPub is a way to keep "the network effect" but keep them separate enough.