Interesting to know that self-moderation has been around since 10 years already but from reading replies in that topic, it's not intended to request moderators to make a topic self-moderated.
In addition, it's a pretty inactive topic.
Assume that I create a topic which isn't self moderated and you make a post. (You may not want to post in my thread if it's self-moderated). Then I make the topic self-moderated and delete your post.
I'm kinda on the fence about this idea; part of me agrees with OP that it'd be nice to switch a thread you created to a self-moderated one in order to get rid of shitposts (which has plagued so many threads on this forum, it's ridiculous). On the other hand, I suspect that if Theymos were to implement a feature like this, it would be the focal point of a massive number of complaints by members who had their posts nuked, even if said feature wasn't being abused.
My request would only affect new replies, after a topic gets changed to self-moderated. All post left before wouldn't be affected. This would prevent abuse of mass-deletion of old posts.
Should a member make a new reply in such a topic which has been switched to self-moderated, our current "topic is self-moderated" banner would be displayed as usual.
Interesting idea, maybe I'll PM a moderator to ask if it's possible and an appropriate solution. Or a moderator can reply here if it's possible.
I just checked (in a section where self-moderated topics are enabled) and we have no option to change a topic to self-moderated.
Many thanks for checking out.