defederating the whole instance without making it clear that it’s a personal decision and not because it actually hosted anything like csam

I think you may need to have another look at the announcement post

We were clear that it’s not CSAM.

To quote that post

I approached the admins of lemmynsfw and they assured me that the models with content in the community were all verified as being over 18.

The post then ended by highlighting that CSAM was not the reason for the defederation, rather, it was the act of appearing like CSAM