I think in your case you’re definitely banning queerphobia/bigotry, which I hope most people agree is radically different from banning dissenting opinions.

Maybe the definition of an echo chamber should revolve more about what would be different if you weren’t in it? For example, I’d say I’m in a community that is an echo chamber if, when getting out of this community, I might change some of my views that previously seemed obvious. I hope that people in a queer community don’t start questioning their sexuality/worth once they’re outside of a queer friendly community - although after writing it out maybe some do :(

But then it’s not the same mechanics: if I come out of an echo chamber I might read up on some new evidence/arguments/opinions that challenge my thinking, while coming out of a queer friendly space is, as you’re saying, getting exposed to hateful comments and being weakened by these. It doesn’t seem right to say it’s an echo chamber, just like it doesn’t seem right to say there are “conspiracy-friendly” communities!