In terms of trying to take down said "Fan Made Server" via a Copyright method, the Zeta Team simply could not do such a thing, unless of course they can somehow convince the world that "OpenBor" (which they use as the game engine) and the numerous iconic Sonic characters are rightfully theirs, which we all know isn't.
Quite simply they have no power to take down a harmless mod of a fangame of a well known franchise (considering it is free to play) and instead they rely on trying to intimidate people with empty threats in order to put them off the idea, all because Zeta fears it may come out something better than what we currently have, which would take all that attention away from her.
At the end of the day, Zeta only does very simple "coding" for the game as of late and most of the art provided does not even come from her, so she does not own much of anything and unless ALL the other developers provide the same answer as what she gives to us, it means absolutely nothing and from what I saw, the other artists are quite open to sharing but Melissa and Zeta refuse to allow it.
If it comes to it and she thinks of using it against people, just remove her character from any Mod that may come along in the future. So go for it, make a Server, I'd be more than happy to join.
Also
JESUSans I'd suggest PMing people the link here for those that are interested because it is guaranteed there are some Project X White Knights lurking around here.