@davidrevoy That is really sad, but not surprising :(.
An alternative I am playing with (but I am very far from having your audience size) is to add a link "Discuss this article on Mastodon" at the end of my posts. With just a link (not inlined Mastodon comments), you give readers a place to comment but the moderation stays on Mastodon side.
@davidrevoy Ah, I too, missed the part where you said your Mastodon instance deletes older comments 🤦🏻