I don’t know this for a fact, but I imagine that O’Malley was “in uniform” at the last conclave so as not to singularize himself. I don’t care much for his apparently self-abasing shenanigans. “Bishop Sean” or whatever just won’t do, nor will sleeping in a monastic cell when the Archdiocese of Boston provides at considerable expense a nice residence as part of its patrimony and expects it to be used. But I believe he has the right to wear the habit of his order rather than a normal cassock under ordinary circumstances, just as the Eastern Rite cardinals have the right to wear their crowns instead of a standard mitre under most circumstances. This is all just what runs through my head, so I would appreciate further informed discussion.