Guys, FYI: I invented saying "lol" on the internet. I have the copyright, but I'm a generous person, so I let it slide when people use my creation. I just wish I could get a little attribution.
Same thing goes with Disney and the Darth Vader copyright: they don't want to crack down on an enthusiastic fan for promoting their character. CC is not cutting into Disney's profit margin, so they don't care. Also, CC may have an argument that what he's doing is a "parody", which is okay under copyright law, especially the red Vaders. However, even though I'm sure Disney doesn't give a rat's @ss about CC and his Vader caps, they are worried about losing their copyright, and if they let too many people use it for free, the copyright can actually become part of the public domain, which would hurt their profit margin quite a bit. So they have to walk a fine line between and losing their copyright protection, but still allowing avid Star Wars (c) fans to continue to be enthusiastic about the Star Wars (c) franchise, which means that they have to allow a certain amount of fan-created items, and even fan fiction. This in the end helps Disney make even more money by selling more licensed Star Wars (c) merchandise and selling more tickets to the movies. Lego recently had a similar internal debate, and has recently decided to embrace their fans and their fan-created items, rather than suing them, as they did in the past.
As for CC making Vaders, like I said before, he would probably argue that he made them for his friends as a "parody", which is perfectly legal. As for CC trying to protect his own copyright, that is also perfectly understandable and totally correct. CC's caps are distinctive and well-known, which is exactly the type of thing copyright law was invented to protect.
And finally, please don't feel sorry for Disney or George Lucas. Please remember that Walt Disney was a virulent anti-semite, a racist, and a Nazi sympathizer before WWII (this is all true, look it up). And as for George Lucas, he stole the idea for his original 1977 Star Wars IV: A New Hope from an Akira Kurosawa samurai movie called: The Hidden Fortress. Lucas did not steal the entire Kurosawa movie, but he did lift a lot of material including the two comedic servants which became the droids. Other parts of his movie were lifted from other movies, he was like the original Quentin Tarantino.