What makes the Catholic vote particularly significant is that Kerry claimed to be a Catholic. As the story notes, when Kennedy ran for president he nobbled a much higher percentage of the Catholic vote . . . the analysis is focussed on why Catholics didn't vote for "one of their own". Mostly because he WASN'T; he only pretended to be.
I think you missed the point of the article. The writer was simply telling the obvious - that Democrats can no longer assume they will get the Catholic vote. They have had a monopoly on this segment of the population ever since the days of the know-nothings in about 1880. No more. The Democrats by embracing the radical feminist agenda have snubbed their most loyal base, a base that has been with them for 130 years.
I agree that in the end, the Democrats have united people of all faiths who are interested in real moral values. Unfortunately for them, they drove them all away.