Joseph, from the way his post his phrased, it seems to me that he’s talking about after he goes before Beis Din, if they tell him that halachically they don’t have the power to force him to give a Get, but they think he should (your case b).
It sounds like he is trying to figure out if he can get away with not giving a get in such a case, since the Beis Din can’t demand that he give one.
It sounds like you agree with all the rest of the posters that in such a case, he has a moral (hashkafic) obligation to do so. Could you please make that very clear to him (since I think he is taking your advice seriously and there can be very serious ramifications involving other people’s lives)? Thank you.