Maybe if we are dealing with a hypothetical question, but the practical effect is (1) it will be more effective as a BC devise than as a barrier and (2) The average Joe will make no such distinction. It will be the annulment question all over again, the same kind of Jesuitical sophistry that Pascal exposed so well.
Yes. Something like this happened before, I believe, in Spain: a Catholic cleric, when pressed about the two evils of protected and unprotected fornication admitted that yes, of the two evils protected fornication is a lesser evil. The headlines were, of course, "Vatican Approves Contraception".
Plus, I doubt a non-contraceptive condom that is even marginally useful in preventing AIDS is possible. But this is the only corner case that I think makes sense theologically.