Maybe due to the free airport fees, no travel tax and no flybe feed (which is how they are operating the MAN hub), it paid for them to open a direct route?
DUB-CUN has being flagged since early 2013, 2012 had 15,000 passengers while passengers for early 2013 numbers were up over 22%. Can't see free fees for a holiday flight being given, reduced but not free. China and Russia are for benefits to Ireland unlike DUB-CUN would be.
TCX currently feed passengers via LGW.