There will need to be an ATR-42 in one of the locations for that to work.
There have been enough flights on Cork-Belfast that we have some idea of the economics of the route and the ATR-72 is just too big.
An ATR-42 in Cork might make a bit of sense. In addition to Belfast, it could allow for increased frequencies on the Bristol route, which could take double daily on weekdays in the ATR-42, but probably only Monday and Friday if you're putting on an ATR-72.
Other than picking off the routes already operated (if that's the right word) by Manx2 at Belfast, I can't see that it makes as much sense to have one based there.