It is interesting to know who actually posts these nonsense posts. If the bounty managers simply want to promote their post by allowing shitposting, you cannot do anything about it. I mean even if you remove the post, the topic moves to the top of the thread anyway right?
If you are referring to bumping your thread with never ending spam, this is forbidden and a lot of threads are deleted because of this rule.
Altcoin threads that are self-moderated are a recipe for disaster. Any criticism that someone points out flaws or accusations of being a scam will be immediately deleted. I actually think certain boards shouldn't have a self moderated option because it limits free speech.
It seem that non moderated ANNs is better choice since then the option of scam acquisitions cant be deleted and then mods can see if the thread is bumped with non allowed techniques