I'm finding Mastodon (I'm at https://nerdculture.de/@kragen at the moment) to be much more pleasant than Twitter, and much richer than IRC. The vicious culture war stuff on Twitter almost doesn't show up in my Mastodon timeline at all.
It's the default, and most instances stick with it. None of the items seem controversial. Which one stands out as a problem to you?
The reason there are no flame wars is not that Mastodon users are somewhat enlightened, as opposed to the Twitter rabble. Instead, clashes are avoided by having (and enforcing) rules and banning ideologies. The catch here is that this would never scale; this only works because there are only a few users.
If an instance is unable to moderate all its users, they can shut down signups temporarily.
In any case, you should contact the admins of your instance, but most probably they have blocked that instance, as it appears on blocklists for being a free speech zone.
Update: I'm seeing them fave my posts.