I now see that the stated intent is to retain anonymized comments as Reddit does

You cite a conversation from November 4, 2022.

A Febuary 6, 2023 comment from developers https://github.com/LemmyNet/lemmy/issues/2624#issuecomment-1419559651 says "The correct way privacy-wise, is to delete your account through your profile settings, which overwrites all your content to remove any info."

The intention is to routinely purge all content of users who delete their account. In fact, there are open GitHub issues about serious performance problems in executing this code, even with a relatively small amount of content. Developers in the past 2 days have commented on this and made no mention of intention to retain content.