Wait, I don't think thats right. Unless I am missunderstanding it?

comment is going to be sent to every version of that post via ActivityPub, as the "true" version has been updated. That is, every version EXCEPT lemmy.world and sh.itjust.works. So users on lemmy.world and sh.itjust.works won't get that comment, because we've been defederated from beehaw.org. If we write a comment, it will only be visible from accounts on lemmy.world, because we posted to a copy, but our copy is now out of sync with the "true" version. So we can appear to interact with the post, but those interactions are ONLY visible by other lemmy.world accounts, since our comments aren't send to other versions. As the "true" version is hosted on beehaw, and we no longer get beehaw updates due to defederation, we will not see comments from ANY other community on those posts (including from other defederated instances like sh.itjust.works)