Around Toome in Ulster Roddy McCorley was always known as a protestant rebel and member of the United Irishmen. His mother was recorded as being a Presbyterian. The fact that her name was gaelic is neither here nor there. Many, if not most Ulster Presbyterians have gaelic names, though they are usually of Scots gaelic origin, eg. Craig, Neil, McLean, etc. In fact his mother's name, McErlean, is almost certainly Scots rather than Irish in origin. the details about his da are not so clear.
One thing you have to watch out for over this sort of topic in Ireland is that there is a definite move by some people of a catholic background to claim certain people and songs which they admire for their own rather than acknowledge than they originated in the "protestant" community. This movement has grown in strength in recent years. Songs affected are, "Sam Hall", "Henry Joy", "Roddy McCorley", "Love is pleasing", "Peggy Gordon", "Carrickfergus",(yes, it may have been translated into Irish gaelic, but this doesnt mean it was from Munster)and many others. The origins of Irish folk songs can be checked in Henry's authorative, "Songs of the People". When a good prod song can not be "nicked" then they sing it badly as a sort of joke, eg. "The ould orange flute" as performed by the Dubliners. This is all part of a demonization process. An attempt at cultural emasculation to prepare the ground for the widespread dismissal of a whole group of people. Its biggest exponents in recent years in Ireland have been the PIRA, but we all know were it was born - Nuremberg! Watch out!