I'm not the person you were talking to but I think you're making the same mistake many people do when they talk about "free speech"; that is, you're viewing it as a case of free speech vs no free speech, rather than the situation we're actually trying to solve which is free speech for bigots vs free speech for minorities.

What I mean is that it's a zero sum game. When you have a privately owned community like Reddit, the choices you make over what kinds of things are allowed to be said shapes the community you build. You can be all for allowing "all kinds of speech" but what that amounts to is the community being a home to a significant portion of racists, misogynists, and other flavours of bigots.

And that's cool because hey, we're all about listening to all sides of discussion and not allowing ourselves to become an echo chamber! Yet, that action of allowing such speech means that most minorities aren't going to want to go there. Why the fuck would a black person willingly sign up to Stormfront 2.0? They wouldn't. So your choice of allowing all speech means that you exclude minority views from your community and don't allow their speech to be heard.

The dilemma therefore, as I say above, is over what kind of free speech you want - the speech for people to say hateful things or the speech from minorities. Sure, for a hard line free speecher it sucks having to choose but the choice should be an otherwise easy one.

As for the idea that removing hate speech and bigotry would lead to an echo chamber, this is just empirically and undeniably false. Many places, organisations, and communities limit free speech and don't turn into echo chambers. Take universities and academic journals, for example. They limit what things you can and can't say, they limit who can attend meetings or who can publish articles, they socially and officially reject people who break the rules they've set up, etc etc, but it would be ridiculous to think that the fields of science and philosophy and history and so on are "echo chambers". They are challenging, thought provoking, often heatedly disagreeing places full of debate and argument.

Banning bigots from a community isn't going to turn it into an echo chamber, it's going to do the opposite. You'll be flooded with a wave of viewpoints and perspectives you've never heard before because previously you've been accidentally shutting them out.