"One of the biggest"? I looked at the instance, it is octodon.social, which does not even make top 50.

These people have an app called Twitter don't they?

It's not one of the biggest and it's owned by one individual, so they can ban who they want. from the about: "hello this is my 'general purpose' instance, hosted in europe. i made it in 2017 to have a good and stable space for myself in the fediverse, and welcome everyone who felt safer here. a feminist, anarchist, communist, cyberpunk culture and many trans and queer people, often with tech or scientific interests."