Sadly, not too surprising
Bill Cork -- recent convert from Catholicism to the Seventh-Day Adventism of his youth -- jettisoned his belief in the immorality of contraception when he swam the Tiber (the other way).
Unfortunately, it's relatively common to see those who once presumably recognized the destructive nature of contraception to abandon that belief when they abandon Rome... the cultural current in favor of contraception is an especially strong one, which relatively few Christians (including Catholics) seem able to swim against. (NB: I'm not psychoanalyzing Bill here... just making a more general observation.) And there's another issue at play here, which might get closer to addressing Bill's recent spiritual wanderings...
Generally speaking, Christians accept the truths of their faith not (necessarily) because they are convinced of the arguments offered in favor of said truths, but precisely because of their faith, their faith in God: they accept as true the things which He has revealed, even if they don't (yet) understand the "why's" with regard to each of those truths. This is in no way to disparage the process of seeking to answer those "Why?'s"... that's exactly what theology does, and it would be strange for a theologian to disparage his own discipline. However, as Christians we don't withhold assent to our doctrines until we have been presented with a proof with demonstrates their rationality... instead, we recognize He who is the origin of those doctrines, and give our assent accordingly. In those instances wherein we do not fully understand a particular doctrine, we can still give our assent because of our confident faith in God, and at the same time we can seek to understand the intelligibility of said doctrine.
For Catholics in particular, this is (or should be) a fairly easy process: because we understand the Magisterium (the pope and the bishops in union with him) to be infallibly guided by the Holy Spirit in the teaching of Christian doctrine, we have confidence that what the Magisterium proposes for our belief is in fact true, even if we do not see the rationality of a particular doctrine at any particular moment. The Magisterium acts, then, as God's concrete instrument by which those who follow His Son can know what He proposes for our belief, and therefore what we can give confident assent to in faith, even prior to an understanding its intelligibility.
What this means is that we do not need to earn PhDs in theology in order to follow Jesus Christ! For if there is not a concrete means by which we know the doctrines which He teaches and therefore what we can give assent to, we are forced to examine each allegedly Christian doctrine to determine if it in fact is authentic Christian doctrine, and only then can we give our assent to it. Such a proposal strikes me as non-sensical: while we are all called to grow in faith and in our understanding of it, the divine pedagogy as we find it in Sacred Scripture certainly does not indicate that assent is to be withheld from each and every supposedly Christian doctrine until every such doctrine is judged as true by the (Almighty!) individual and his quasi-divine intellect. In addition, it's ahistorical: although the Church did not substantially and dogmatically articulate its Trinitarian & Christological doctrines until forced to by the Arian heresy, Christians before Arius still assented to the truths which were precisely formulated at Nicea and the other early Councils. And we're seeing the same thing today with regard to the reservation of ordination to men alone: the theological arguments which explain this teaching are only know being thoroughly developed (because the teaching has been challenged), but that doesn't mean that Catholics who lived centuries ago did not believe this teaching... they in fact did, despite the fact that they were not presented with elaborate theological argumentation in its defense.
I praise and thank God for giving us the Magisterium; even though I do have a doctorate in theology, I have just enough self-awareness to recognize that if I had to arrive at the intelligibility of a doctrine prior to giving my assent to it, the content of my faith would be extremely sparse. Thankfully, I don't have to do so to revel in the truths which God has revealed for my salvation.
(Feel free to offer your critical comments... this line of thought is very much a work in progress.)