As I recall, Dr. Keyes always said that Bush couldn't articulate the moral message in the context of him against Gore. And then at some point after he did that study and that prof from AU did the study that showed the WH doesn't change in economic good times, Keyes was stressing that much more the need to address the moral issues.
The moral arguments were not used in the debates...since the questions are controlled by the moderators. If President Bush had tried to drag abortion into every question, the way Dr. Keyes does, he would have looked like a fool, been accused of pandering to the right wing, and LOST. As it was it was close, due to democrat cheating, the DUI, and network blackouts of Bush for over a month after the democrat convention.
As far as the Keyes, McCain, Bush debate, I do believe there was discussion at the time about whether the networks would carry it if Bush didn't show up, since he was the frontrunner. I don't have a source for that except for my memory, so you will have to take my word for it or not.