You can mute folks - it is totally up to you. That ends up being a very powerful vote IMHO.

For the rest of it: I love the quote (which I will paraphrase) that free speech is awful but censorship is even worse. 

Relays - I personally need to study them more. I'm pretty sure that each relay has the option of censoring as it wishes; the power of nostr is that you can use multiple relays and even host your own.