True. But it's still not fair. But it's also not confirmed that there is such a rule.
I can confirm there is such a ban. The head of CBS legal gave it to me personally.
And, personally I think it's damn fair. The reason is simple: they will not allow any direct competition to the franchise's current money maker. They give us so much and ask so little. "Don't take away any of the money we can make from what we own and are making money from now"
It works this way. Say a fan loved Star Trek, but then thought Star Trek Into Darkness sucked big time and didn't agree with how JJ handled the characters. Well, in steps BigJJFan Productions with THEIR sequel Star Trek Into Light. Fan then starts pumping his money into BigJJFan Productions and promoting it all over the web. Well...there's a bunch of cash and PR and talk not going to CBS's cash cow.
We're pretty lucky that CBS legal considers all other fan films as adding to the interest in JJ Trek.
If you really want to do/see a JJverse fanfilm I am sure you will get to see one. You just have to wait until CBS gives up on the cash cow and lets Trek go into hibernation again. Then it won't be competition.
(And to clarify: CBS owns Star Trek and the merchandising. They "gave" the license to Paramount (for the time being) for the feature films. So...it all kicks back to CBS. And, well, all the toys, glasses, uniforms, etc that is sold because of the feature films is by CBS and they are the ones profiting from it. ALL Paramount makes money from is the films themselves.)