The hashtag could have its own nip backend where the creator can assign other owners, admins and moderators, like a chatroom that posts to the main timeline. You are only allowed to post to the hashtag if you're following the rules and haven't been banned, and your posts can be marked by the mods as inappropriate.

Someone flamed at me about grownostr "you don't own this hashtag" which is true but it would be nice if someone did.