When you say "Once you know - you will understand why it would make things more complicated." that makes me worry that it's a bad thing...it's not Cryptic is it?
Really that phrase could be practically anybody who has ever been mentioned or theorized as all of them have complications being known would cause. They could be hiding from view or outright lying about their buyout interest until it is a done deal so it isn't disrupted by nagging questions. Some examples off the top of my head:
* PWE/Cryptic - Has past history with NCSoft which may not all be positive, a reputation for game alteration, and a competing product. It would be a forum mess.
* Missing Worlds aka CoT: Building a competing product which they kickstarter funded for and might have difficulty convincing people they should abandon or duel develop with CoX.
* Plan Z Studios aka Heroes and Villains: Building a competing product and... okay I don't really see Golden Girl being behind a secret buy out offer, but few people are as big a fan of CoX and I'm trying to be complete here.
* TitanNetwork: They would have to maintain an image of impartiality because if the buyout failed they would still need to maintain there existence as CoX hub.
* Infogrames / Atari - Again? There is a lot of back and forth ownership with Hasbro, which is connected to D&D, which is connected to
NCSoft (OOPS EDIT) PWE.. Its a lot of corporate messiness.
* Members of Cryptic planning a breakaway - Successful or not, PWE would be mighty unhappy with internal staff planning to sneak off and restart a competitor.
* Former members of the Paragon team - Allegedly involved in previous failed buyouts, so to much publicity could help reawaken whatever broke down the original attempts. Also a lot of emotion involved on all sides.
* SOE or Disney - Own competing products and are somewhat scary: People would be concerned over what this would lead to (i.e. is it just buy to kill).
* Valve/Steam - Distribution sure, but MMOs? Would just get hammered by questions.
* Random rich people - Raise the issue of their development capabilities (which they could pay for I guess, but still).
* Activision Blizzard or EA - Reputations built for good or ill on current game stable. Would raise concerns about alteration to the franchise.
Note I'm not advocating any of the above, saying its any of the above, or even believing its any of the above. I'm just saying there are plenty of reasons to keep the deal hush-hush for most of the usual suspects.