Irrelevant of the moral issues that this poses, such content is illegal in many countries (e.g the UK). Continuing to federate with lemmynsfw.com will put users at risk of significant legal repercussions.
Please would the admins consider defederating unless lemmynsfw change their policy.
UPDATE: The lemmynsfw admins posted an clarification here: https://lemmynsfw.com/post/29826. My original argument for defederating doesn't stand any more.
The other issue is that lemmy.world users that subscribe to it will cause the content to be cached on this server too which could create issues for the admin.