apparently the info was posted (by Disney) to its Facebook page and there was some other release of the information that you could enter Galaxy's Edge 1 hour prior to your reservation time, if you couldn't just walk in otherwise. That was to give you time to report to the venue you booked inside Galaxy's Edge. However, WDW hasn't clarified this on its website.
I don't think they can exclude reservation holders if there is a wait to enter the land, on the basis that you're talking $100 to $200 penalty for the droid/lightsaber builds if you are a no-show. I am sure WDW is not interested in having to process after-the-fact waivers for a lot of no-shows. Oga's would be $10 pp and that could also be a pain if a lot of reserved guests missed their reservations because they were made to wait outside the land.
another thing to consider is the amount of time it might take to enter Hollywood Studios itself - I'm going the second day, not the first, and I'm sure they will add extra bag checks, but i'm always behind the person carrying 3 backpacks that have 17 zipper compartments each and 5 bags inside each backpack.