I've posed this question before and they have absolutely no interest in enabling auto-download, making the maps available as Impulse-downloads, or even including them in patches or as a custom map bonus pack.  They've added a few other Ironclad or Stardock-made maps but as far as I know never asked any of the custom mappers if they could include their maps and I've volunteered my maps before.  (I don't understand why they wouldn't be interested since adding high quality custom maps made by players would increase the value and desirability of their product to purchasers for free.)

For the record, I'm pretty sure we've never received a straight answer about why the game didn't allow auto-download for custom maps to begin with.  It has something to do with "permission settings".  Perhaps they were considered that some cretin my send out a virus as a custom map text file or make a map with vulgar planet names or an arrangement of planets to form a vulgar word, etc.

The only thing they need to do with regards to copyrights is ask for permission and keep a record of the response.  If they were smart the Galaxy Forge EULA should say something about their being able to include your maps in patches and map pack.