My experience with self-moderated thread is very normal like any other thread. The only one that got remove or delete is usually off-topic or spam without any contribution to the thread. Most bounty thread today are just filled with weekly report posts so even if they are self-moderated, no one seriously uses it for any discussion.
Yes, I also agree with your words. Usually there are no extraneous conversations in the bounty thread, except for reporting. All questions about the bounty are resolved in telegram groups. Therefore, I also don't see anything criminal in these threads. But this is just my experience.