Hey, guys! Thanks for the discussion here \o/
What could work pretty well is to keep the Writings category blocked for publishers, and when a writer wants to submit their manuscript (preferably after going through community revision) they would post it as a PM that includes the publishers, as @simon said here:
I think it makes a lot of sense to have one more step when sending your writings to publishers, since it’s an action you’re going to give some thought to before taking; posting your work for revision by the community, on the other hand, should be something you do without concerns.
Also, the forum wouldn’t be cluttered by similar categories.