No, St. Patrick was not Irish!
If at all, he is Scot having been born in Scotland of Roman parents, who were in Scotland as "overseers" of this (Scotland) Roman territory.
He did go back to Ireland already a Bishop long after his sojourn there as a slave (captured by marauding pirates into the British Isles when he was only 14 but escaped when he was 20 so the story goes) to evangelize and convert the heathens which he did successfully for the entire nation of Ireland.
He died in Ireland and all these events in his life happened in the 4th-5th Century. At that time, he belonged to the undivided Church and East and West should be able to venerate this very popular saint.
Being "Irish" once a year has become a "tradition" among many, including our City of Chicago, which celebrates the Saint's feast day with 2 "official" parades for Northsiders and Southsiders. Heck, the city even colors Chicago river (including all of its branches) green for crying out loud.
Chicago mayor, Richard M. Daly, who is an unabashed Irish, and aspiring pseudo-Irish politicians vie for attention during the parades participated in and witnessed by numerous ethnic groups over and above the authentic Irish.
For his unbelievable work in Ireland, no wonder he IS the Patron Saint of that country and and of all Irish throughout the world!
Let's celebrate with them and drink all the beer and eat all the corned beef until we are green in the gills!