The transition from fun to business is fraught with problems. This upends my theory that Ben was moving to pinball full time from TBHS.
There's not much info in that post but it does show what would seem to be one side of the problem. "Delayed beyond my liking" and "Creative differences'" seem to suggest Spooky had to make hard business decisions and Ben seems to want to be able to influence that more than a contributor can normally expect. That's bound to be an irreconcilable problem in any project.
Its all speculation, but hope that they can still be friends if they can't work together. There's a lot of good history there. I certainly support both, together and separate.