I agree with you. Lewis seems to be on a spiritual pilgrimage. He goes from atheism to theism to Christianity. I have no idea where he would eventually end up if he were alive today. I have a couple of friends that go gaga over Lewis. Steve Mueller, who now teaches at Christ, Irvine, did his dissertation on Lewis’s Christology. I was at his oral defense, and the question about Lewis’ belief in purgatory never came up. I wish that I had known about this, for I would have asked him about it.
I took my undergraduate degree in history but had an awful lot of English Lit (my university didn't 'do' minors) and when I got into Lewis's volume of the Oxford History of English Lit I was completely amazed at the scope and depth of his reading and knowledge. But it's really not surprising - I mean, a Triple First is usually an indication that a man has got it together academically.
I don't know about you, but I always think of good questions to ask long after the opportunity has passed . . . not academically speaking of course but in the courtroom, which was my day job for years. Defending a dissertation probably has something of the feel of standing at the podium in an appellate court and getting peppered with questions from the bench. (Thankfully there was no requirement for an oral defense of my thesis -- THAT would have not been fun at the time. It would be fun now - of course I could have done a much better job of writing it now - education is wasted on the young.)