We've blocked some fediverse instances that don't fit with the sort of positive space we want to create. We're using the @blockchain from https://github.com/dzuk-mutant/blockchain/blob/master/list/list.md.
Only domains with illegal content are outright blocked. Others are silenced from the federated feeds, but if you want to follow anyone on them, you can; knock yourself out.
If you have any problems, or can't access accounts you really want to, let us know!