Very appropriate for neo pagans like de Blasio and Walsh to exclude themselves from participating in a Catholic celebration. They do not share or respect the values or beliefs of Catholicism. Their presence would have been a hypocritical intrusion. Also the real Sam Adams was a viscious anti Catholic bigot, a failed brewer and made his living as a dishonest tax collector. Its ironic that the beer company is carrying on in the tradition of its namesake.
It’s pan-Christian in concern; St. Patrick did his thing well before the Orthodox/Catholic split.