I missed this op-ed a couple of days ago. Mario Cuomo has clearly learned nothing from his exchange with Douglas Kmiec, since he repeats most of what he said then, arguing that if conservative Catholics give Roberts a pass for upholding the Constitution (over against his "deeply held personal beliefs"), then they should also give Catholic politicians like Kennedy and Kerry the same leeway.
There are at least two things wrong with this argument. First, Cuomo doesn’t distinguish between judges and politicians (which isn’t a surprise). Judges aren’t supposed to vote their consciences; their "office" is to interpret the law. A political leader can act on his or her conscience, working to change the Constitution, if need be. If a judge worked to "change the Constitution," by (say) reading into it provisions that aren’t there (however otherwise desirable they might be), he or she would be violating his or her oath (or affirmation).
Second, what troubles conservative Catholics about Kennedy and Kerry (here I’m speculating, since I’m merely a conservative ex-Catholic) is not that they refuse to act conscientiously to uphold church teaching against the Constitution, but that it’s not clear that they actually "privately" support church teaching.
The good news, such as there is, from this article is that Cuomo is looking for ways to leverage Roberts’s inevitable appointment to the Court to get his friends of the hook onto which they have wriggled. He argues that Roberts should be taken at his word when he promises to uphold the Constitution, and that the Kerry/Kennedy version of the Constitution should provide them with all the cover they need to go on their merry ways.