I think that's fundamental to Nostr tho. There is no instance that decides what's hate and what's not, or which notes should be shown or not. It's really up to the individual or group of individuals to call these people out or block such people. There have been approaches about a year ago. In Amethyst when x people report someone they get practically shadow banned for everyone in that circle. There was a lot of discussion about censorship and misusing such a function (which I can also understand). It's a tradeoff with having a centralized instance to decide what should be shown, be it good or bad (meta, x etc) or not having that (as with Nostr). Freedom of speech also includes dumb and mean speech. I think the issue is existing on all platforms, even if someone gets blocked so they don't see your content, nothing prevents them from making another account etc.

I really think calling bad actors out is literally the only thing to do (besides muting/blocking/not caring to much about everyone's opinion) It's up to each of us to keep Nostr an enjoyable place for it's users.