Yeah it's worth noting that blacksky provides accounts to non-black users but their posts don't get included in the blacksky feed. And non-blacksky PDS users who are confirmed black still are allowed to be included in the blacksky feed.

So it's multiple components really.

- The blacksky feed which is a curated feed and community built around the US black community on atproto.

- The blacksky client, appview, moderation team, and relay which provide the necessary infrastructure for blacksky to operate independent of the rest of the ecosystem if they need to and for them to tailor their experience to their community.

- The blacksky PDS which serves as a source of truth for data storage and auth for blacksky users that choose to use it.

And of course non-black users can use all of this infrastructure but if you aren't black and you want to host your account on a blacksky PDS you have to pay a small subscription/donation.

It's all for their community but they are more than willing to let other people use their infra as long as those people pay their fair share.