This is James Cameron's script for Aliens. Notice it doesn't say "Property of 20th Century Fox" on it. Does that mean the script belongs to James Cameron?
http://www.dailyscript.com/scripts/Alie ... draft.html
A script in which you're commissioned by a studio to write using pre-existing, copyrighted characters belongs to the studio, not to you. You're doing the work for the studio. Therefore Barker (or Cameron for that matter) couldn't just decide to publish it online because they felt like it. They'd need studio permission because the script doesn't belong to them.
Now, if Barker did it strictly for pleasure and wasn't paid and didn't pretend he was hired by Toho/Tristar to produce a script, then he could publish it online without studio permission.
I'm sure that Rossio and Elliot got permission from Toho and/or Tristar to publish that online. If not, what's to stop me from writing a "Rocky" movie featuring Rocky, Paulie and the gang (characters that don't belong to me and I didn't create) and claiming the work as my own?
Any entertainment law scholars out there that want to correct that summation? Or am I on-base?