Oh yes, anti-Catholic bigotry is clearly dead and buried. </sarcasm>
As I understand it, the author's point is that a statistical minority of Catholics are social conservatives, therefore it's technically incorrect to claim that any bigotry is anti-Catholic and not anti-conservative Catholic. Likewise, the author would say it's technically incorrect to claim that conservative Catholicism represents all of Catholicism, or even a simple majority (remember the 80S bumper sticker "The Moral Majority is Neither"?)
Of course, this argument is utterly and laughably ironic, because it means this political liberal author is actually arguing in favor of committing bigotry against a statistical minority.