Is it possible to create a free speech reddit alternative that doesn't immediately turn into a right wing extremist site? My mind immediately turns to the Paradox of Tolerance, and I think the answer is no.
You’re offering a comparable product except with no real existing user base and a higher friction to gain new users for your community.
There’s some marginal audience in people interested in the principle of the thing, but the bulk of your users are going to be users that can’t be serviced by the main players.
If your only offering is “X, but we won’t ban you” then you’re going to collect the dregs of the internet.
There’s a bit of a feedback loop here as well in that many of the existing services are banning users and communities because they’re negatively impacting advertisers and the rest of the community. So when your service is overrun with the undesirables in short order, the rest of the communities are going to be negatively incentivized to migrate and you’re going to find it impossible to find any real financial support or backing.
So no, I don’t think “X, but free speech” will ever turn into anything but a cesspool. You need an offering that will attract desirable users as fast or faster than the undesirables that have been kicked out of anywhere else can sign up and that’s going to take some sort of additional value.