I don't see how the mere act of wearing what amounts to a family heirloom falls into either of these categories. There's no evidence that he's intending to lead anyone into sin by wearing the ring, and I do not believe that anyone can honestly say that the act of wearing a ring does, by its very nature, lead anyone into sin.
The problem is he is wearing what appears to be a wedding ring on the ring finger of the left hand, which is the finger and hand a man in the United States would wear a wedding ring. No person seeing him would naturally think, "Oh, how nice, he's wearing a family heirloom. He must really have been a good son." No. A stranger on the street sees him in public and, given what Bergoglio has said about homosexual priests (you must remember, it made the news, "Who am I to judge?") sees what appears to be a married Catholic priest--and, knowing Catholic priests can't marry women, assumes he must be an openly gay Catholic priest.
Frankly, it seems that this situation fits precisely what scandal is in that the priest is doing something that will give people a sinful view of the Church. He may, somehow, not be guilty of the sin of giving scandal if he is just simply too dense to realize the problem, but it seems strange that even a Novus Ordo priest could be that
dense. Likely, he knows exactly what it looks like to others and just doesn't care.