The guy who wrote the article just doesn't get it. Thought so much of the celebration around St. Patrick's day has taken on a secular connotation in modern times, it's still a saint's feast day on the Roman Calendar. In terms of the heirarchy of memorials, feasts and solemnities on the Church's calendar, Mondy of Holy Week "trumps" St. Patrick's feast day. Ordinarily, when something like this occurs, the saint's feast just doesn't get celebrated that year.

However, because of the popularity of St. Patrick's feast, not only in Ireland but wherever the Irish have settled (i.e. the USA especially), the Church has decided to move the feast day so that it can still be celebrated that year. And it's not the first time this has been done. In 1940 (I believe that's the correct year), March 17 was Palm Sunday, so St. Patrick's Day was moved that year, as well. In other words, this is something that the Church does occasionally when circumstances demand it, and nothing really to get excited about.

What this mostly has to do with is liturgical celebrations (the Mass and the Divine Office, to be precise), so if you are not a Catholic and not involved in those liturgies, it really doesn't affect you at all.

However, I couldn't help but think that the 15th will be on a Saturday and that most secular "St. Paddy's Day" activities will likely be on Saturday rather than Monday, regardless.