I think Achilles is spot on. We know from other threads that PoC would like to get all 7 wonders, and when Ascension had their mini-implosion, it looked like PoC could achieve that goal without openly violating any pacts. (yes, OPENLY was the key word. Come on people, are you STILL not aware that bison bam broke ascension's wonder in 23 under PoC orders?)
But some crazy fool got involved and now one of their wonders is blocked. They couldn't reconquer the city on their own, so let's assume the obvious reaction. They make a deal. 10th gets in on the prize, and PoC gets that little boost which will push them over the edge. Of course, some crazy fool hasn't been sitting on his hands the whole time. He's been goading certain members of Ascension all along, and finally smiles to notice key ghost cities starting to vanish.
So if Ascension pulls back together and finishes their pyramid, PoC is STILL blocked from ultimate victory. At this point, an attack on Ascension isn't pretty far fetched. If you're willing to side with the enemy in order to win, why wouldn't you side against your friends?
Now, like any good hypothesis, these assumptions provide us with a couple predictions that are testable. PoC ought to be highly concerned with appearances, that Ascension not know this battle with Sapphire is only a prelude to something larger. So they should attack any claims of such impending actions in the forums. Check. There should also be an increase in activity against that crazy fool causing them so much trouble, particularly from those close to him, for such activity can be used to imply his judgment is not impartial, and that his warnings to Ascension need not be given full credit. He is "stirring things that are cool" perhaps they will say. Check again.
Hypothesis passes. Becomes leading theory. Your move.