Well, if she were Irish she would be betraying the Catholic Ireland of her fathers, certainly.
But the topic title says she's Irish American. So there's nothing at all traitorous about it, since America is not, and never was, a Christian nation. America was founded, in part, in order to grant men the "right" to believe whatever false garbage religion they choose. Error does indeed have rights here.
In fact, recall the words of the Treaty of Tripoli signed in 1798 by John Adams:
"The government of the United States of America is not, in any sense, founded on the Christian religion, as it has in itself no character of enmity against the laws, religion or tranquility of Muslims."
Something for some of our more jingoistic members to ruminate on.