Here you go!
https://community.nodebb.org/topic/9447/howto-inject-hidden-data-into-composer/8
This should get you started. You'll need to edit the composer.tpl, or inject html at composer load, checking if the post is a new topic.
Its possible to assign a group the moderating power on just one category, However be aware that this will also include other moderation powers such as Forking, Closing and Moving topics.
