How to do it: user selectable curation/filters/moderation without requiring an account (explicit web pages or/and URL parameters). Actually, an "official" curation/filter/moderation could be the default, and users would have to take up steps to go no curation/filters (https://www.freedomofspeach/forums?zero_moderation=on)
There is always the issue of children/young teenagers: the only reasonable option is proper parenting regarding internet access, and we all know it is easier to say than to do.
Obvious side effect: if you keep all the trash, you will need bigger technical resources and very probably, ppl won't turn off the default curation/filter/moderation and this trash will be sort of technically "costly".
I don't think it's censorship to put resource limits on services, as long as they apply equally to every account (and companies can obviously try to limit accounts to one per person).
In fact, I think it's even reasonable to say that your resource limits can differ based on how much you are willing to pay, or how much users like your posts.
At the limit, if you're sending spam (which no one wants) then all your posts will be disliked, so you are granted zero resources and can't send any more spam. That reasonably balances one person's right to free speech against everyone else's right to not have to listen.
To their credit, the author does suggest that there should be a free market in which different companies can experiment with different moderation policies. They even, correctly, suggest that what's needed is some sort of interoperable protocol to allow people to communicate between sites (which hopefully will be required by the EU's recent DMA proposals[1]).
What's missing, though, is the possibility that a company could let users choose what filtering they want without having to abandon the platform and start somewhere new. So, for example, Twitter could by default ban conspiracy theories and misinformation, but if a user is an adult then they should be able to opt in to see that sort of content. That would respect the principle of free speech while still allowing the site to continue to look almost the same for almost all users.
[0] https://en.wikipedia.org/wiki/Politician's_syllogism
[1] https://en.wikipedia.org/wiki/Digital_Markets_Act#cite_ref-:...
https://www.buzzfeed.com/stephenlaconte/conservatives-love-c...