I'll bet if the UN had issued an edict on the subject he would have followed it! Note that the church in question is only "Catholic" in the most liberal sense of the word:
The Paulist Center attracts Catholics uncomfortable with some of the Vatican's orthodox teachings or who otherwise feel alienated from the Roman Catholic Church.
The congregation includes gay couples, whose adopted children are baptized there, unlike in some other Boston parishes. In November, its leaders refused to read aloud during Mass from a letter opposing gay marriage, as requested by the Massachusetts bishops.
What I don't understand is, if these so-called "Catholics", including Kerry, feel "uncomfortable with some of the Vatican's orthodox teachings or who otherwise feel alienated from the Roman Catholic Church", why don't they leave? Wasn't that what the Protestant Reformation was all about? There are scores of Christian denominations that would welcome people with these points of view. Traditional Catholics, in turn, would feel more "comfortable" with people who defer to the Vatican's orthodox teachings.
I'm sorry if that offends, but the arrogance of people who want to destroy the traditions and orthodoxies of the past, just because it doesn't fit their current "lifestyle" are annoying in the extreme. Religious belief is not intended to conform to your lifestyle, your lifestyle should conform to your religious beliefs. That is the whole point! Isn't that obvious?