What I do not understand is: Even if the 51% attack had been fully successful, how did the attackers think they will be able to liquidate 9.7m CSC?  Surely, their objective must have been to illicitly gain the CSC and then sell them for BTC and walk away with the BTC.  Given the historic market depth, that seems nigh on impossible without crashing the price to zero. 

So, something is fishy here.  Why would an attacker go to such lengths only to end up, even in the best case scenario, with 9.7m CSC that are practically unsalable?

Unless of course the attackers were insiders and had other motives, such as taking over a large part of the coin supply.