A decent approach, as a social platform, would be to use the Reddit model. The content is stripped and replaced with [deleted] if deleted by the user, and [removed] if removed by moderation (with the appropriate log in the modlog). This should maintain the overall comment chain.
I think the issue may be federating the update to other instances. I’m not sure how it works now, but if it’s treated as an edit, that should work like they currently do.
You assume they could figure out that you’d be making fun of them. I think they probably lack the critical thinking and self-awareness for it to matter.
I’ve said many times that I can’t get rich off of stuff like this because I have a soul and wouldn’t be able to be ok with parting fools from their money. That might be you, too.