Ask Zurtle* for more details. As one of the TWA members I worked most with, he might remember. It had to do with several issues. One, I outlined in the DS thread here:
http://forum.tribalwars.net/showthread.php?p=4948496#post4948496.
Zain was the only other Apoc leader who knew. It was a long time ago. But it was planned.
What you're structuring here is a simplistic "straw man". I never said BA and Apoc are "chummy." I never characterized the relationship as anything other than one born of trust, communication and time-consuming work. Obviously, this was to further the goals of both families. It is pretty standard game theory, actually. We played by a set of rules that all agreed to. And we trusted each other to follow through when our members broke those rules.
Here's another little secret from the UA split...
It didn't really change anything. Zurtle* can affirm - there was concern among UA leaders that the constant propaganda against the UA was creating morale problems inside the rank-and-file. There were some leaders who suggested staging a "fake split". I believe Zurtle* thought that this was the best route to take. At the same time, there were the issues with DS -- who actually WANTED a split. BA leaders had grown weary of the bickering between the leaders of the various families, and so we said -- let's do it all.
So, I (with Zurtle*'s and Zain's knowledge) helped remove BA from the UA. For people who did not know, it appeared to be a major rift had occurred. And there had - but it was between DS and TWA. Not BA. We just took the opportunity to save the alliance, avoid a DS bloodbath, keep active DS players playing the game, and continue our wars against T~S, GOC, FUSE, and A/S without adding another tribe into the mix.
This is not to say that BA's split from the UA was "fake." It was real. The UA governance structure did, indeed, go away. But the ties BA and TWA & RKN had continued.
And if you don't know... now you know.