I see it like this...

Due to a bug in code on the c-cex exchange, someone found their account with a ton more bitcoin in it than there should be.  That user then made a conscious decision to trade the bitcoin which was not rightfully theirs.  Everyone on the other side of those trades were technically receiving stolen property.  The non-existent bitcoin (it's just a virtual exchange balance remember, not an actual bitcoin wallet) was converted into darkcoin by trading on the exchange, effectively transferring the non-existent bitcoin into other traders accounts.  The dirty darkcoin was then laundered (or tried to be) by trading for bitcoin on poloniex.

It seems both c-cex and the user who was consciously involved in this are making a great effort to retrieve lost funds.  Problem is, due to the trading at great loss, a large chunk of this bitcoin that never existed in the first place is now in the hands of everyone with whom they traded.  This is why your bitcoin balance at c-cex is frozen.

If authorities were involved, the accounts at poloniex would likely also be frozen during the investigation period.  If this were a bank error of similar scale which was deliberately taken advantage of, the person involved could end up with a prison sentence.

Yes the flaw was C-CEX's, but let's not forget that ultimate liability lies with the person who took advantage of it.  C-CEX is as much a victim as anyone else in this situation.  Yeah it sucks, but that's the way any legal system would see it.  If your car is stolen because you left the key in it, you made a stupid mistake, but you are not responsible for the loss - the theif is.  Any forex broker would reverse the transactions without question and you'd just have to suck it up.