I still had to write a BadZone function for this one, despite my efforts with the captureMatrix parameter. Because the ban on capturing Kings with the capture move for divergent pieces is dependent on the move, not just on the piece type. XBetza can indicate a move can only capture royalty (k modifier), but not that a move can capture anything but royalty. I suppose I could make an XBetza extension for that, by adopting the convention that the combination kc means non-royal capture. This would otherwise be a useless combination, as c already includes capture of royals. So k becomes a kind of toggle modifier, which negates the possibility to capture royalty from what it would have been without its presence.

[Edit] This is achieved now, and the Diagram now is working without any custom scripting.