I'm trying to be as polite as possible LoU.
If you don't want to share that respect, forget I asked.
However.. I would prefer that you answer my question...
JKA is not free and it is owned by STAR WARS.
If a player holds the files of a mod for JKA, what legally keeps players from editing them?
I'm not LoU, but I will try to answer.
I think it means that it's about rights of =tom=; He made some work, he gave a permission to REDISTRIBUTE his map, but =tom= didn't give a permission to MODIFY his work, and nobody can do it without his explicit permission.
You can find more info here, it's explained detailed:
10 Big Myths about copyright explained
As for Disney, it seems they allow people freely ports stuff between any Star Wars games:
Updated EULA Regarding Porting Content - Ideas & Issues - JKHub
Though I'm not sure that this it what LoU meant. Just my guess, nothing more.
But my personal opinion is that Movie Battles team interprets copyrights much more stricter than they should and could (no offense).
We could safely assume that =tom=, as well as any other modder who made his product public, actually doesn't mind from modifying and redistributing his derived work (with an exception of explicit prohibition, indeed).
Also it would be nice if Disney made additional changes to EULA, restricting any limitation from modification of deriving work in the same way as GNU GPL does;
Like if do any edits to GPLed software, anybody can edit your work and then transmit, publish, print it etc etc, and you absolutely, positively can do nothing about that.
Because it's GPL. Because anything you do with GPLed software is automatically under GPL, too.
Also my personal opinion is that the whole current copyright system is a joke, Berne copyright convention is shit, and almost everything about copyright laws and regulations must be changed ASAP...