Like BitTorrent, you choose which repos to mirror. If you’re crazy or you watch your server like a hawk you could just choose to automatically mirror everything.
Like BitTorrent there is no way to “moderate” what another node chooses to share.
They are working on tools to help permissive nodes remove repos flagged for deletion, but the protocol itself does not prevent a node from ignoring this flag.
I had a few different issues getting the CI broker working the way I wanted to (don't even remember what the issues were, but it had to do with catching patches) so wired up my own way but simply polling via Git - using a thing I built a while back called goa (gitops agent) for another project.
The tricky part was getting the output from what ever do with the code, back into the Radicle patch. But it works.