I think in this context it's meant on a technical level: as far as the fediverse is concerned, there's not a whole lot instances can do. Anyone can just spin up an instance and bypass blocks unless it works on an allowlist basis, which is kind of incompatible with the fediverse if we really want to achieve a reasonable amount of decentralization.

I agree that we shouldn't pretend it's safe for minorities: it's not. If you're a minority joining Mastodon or Lemmy or Mbin, you need to be aware that blocking people and instances has limitations. You can't make your profile entirely private like one would do on Twitter or any of Meta's products. It's all public.

You can hide the bad people from the users but you can't really hide the users from the bad people. You can't even stop people from replying to you on another instance. You can refuse to accept the message on the user's instance, but the other instance can still add comments that don't federate out. Which is kind of worse because it can lead to side discussions you have no way of seeing or participate in to defend yourself and they can be saying a lot of awful things.