Perhaps, but your reasoning is a bit too vague to be convincing. So what am I missing? Beehaw registration is open. I had no problem getting an account there; over Tor in fact. I don’t recall if they were using the Q/A interview field back when I signed up. OTOH that screening mechanism has become quite typical these days.
W.r.t defederation, I only know that Beehaw defederated from centralized instances, which is fair enough from the PoV of those embracing the decentralization principle. I skimmed through their several page long policies which boil down to “don’t be mean”. So I would guess they defederate from hate-rich nodes - not sure. What specifically do you have in mind?
The Cloudflare instances I listed are walled gardens because they restrict access hard and fast to various demographics with arbitrary exclusion of various groups of people (which IMO is an even harsher form of walled garden than some of the corporate walled gardens). I would not call having a code of conduct indicative of a walled garden, otherwise we would be calling just about every single instance a walled garden and thus not a useful place to draw a line.