I was under the impression you had to already own Rebellion to even order the collectors edition. It's really just a game merchandise pack, I don't think it comes with a game key. And even if you did have it you'd have to download it with steam.
Wait so are you trying to tell me that I have to by the product key seperately? Then what's the point of getting the disc?
As a collectors item and I guess it will make it so you only have to download a small update to the latest version, so it helps those with limited bandwidth. A lot of people asked for it anyways even though I don't understand why you'd want it either. Some people just don't feel comfortable unless they have something on physical media, even though without steam I think it's useless.
Also from the collectors edition email.
*Game CD Key NOT included. Please note that these items are no longer being shipped in a "Collector's Edition Box."
**Game CD Key NOT included.