"So I do prefer an open social network without censorship and moderation. There will of course be discussions. But I see that as much more fertile than a central body of faceless Facebook moderators."
Rather then being without any censorship I'd like a censorship, which can be freely choosen on every account.
Like add different filters, what for example nsfw means for that account and every post within these filters is tagged as nsfw or banned..
I think you can already both ban nsfw and hide users that you don't want to see... but I am not really sure. If not I guess it will be a feature in the future. But I wouldn't call voluntarily avoiding things for censorship.
No matter what none of these things will not work 100% sureproof for you. If people does not tag themselves you could be exposed to bad, bad things anyway - you need a protocol and a surveillance -staff to prevent such things.
One person's filter is another person's treasure. I used to think just a general NSFW toggled in everyones backend settings would be enough, but now I think the ability though needs to be there where you can filter out any hashtag. If people start abusing that I think that is where flagging and reporting posts will take care of these issues naturally.