I am also unsure about lemmygrad, as although I dislike the instance, (and a few parts of db0 as well) I do agree with defederation being an extreme option.
::: spoiler unrelated note
I am concerned about the defederation system as a whole, as an instance could defederate with all but the most extreme left/right wing instances, causing an extreme echo chamber to develop. (albeit only on lemmy)
:::