I think this is the answer. A PhD becomes it's own monster. Several years dedicated to a single project, it becomes a personal part of your identity. The thought of allowing that to stand up against scrutiny to other professors is a tough thing, and back then there weren't such limits on timeframes. As the mental block of submitting it becomes higher, and time moves on, and you get busy with a new job, family life, it gets harder and harder to do that.
The strange thing is that he is reported to have submitted a copy and gotten thesis committee approval, so it should have been just a matter of getting it bound and filed in the library. But mysteriously he didn't take this last seemingly trivial step.
That seems strange, odd to throw out all away at that stage, when all the work has already been done and the expense of typesetting it has already been paid. Getting it bound is relatively less, unless they wanted more than one copy.
Maybe he disagreed with the corrections? Or maybe he had run out of money to correct minors? Maybe the reviewers were critical and he was annoyed by that.
