Well, first of all, why not? He’s losing.
From a piece I have running today in LifeZette:
By proposing a debate where comment is restricted to economic issues, Trump could occupy the moral high ground, a place where he has had plenty of trouble standing, even against Hillary Clinton.
Instead of showboating TV journalists, Trump could demand that actual economists moderate the proceedings, or other parties — perhaps former federal judges? — deemed more neutral than the fourth estate. There is no intrinsic reason why journalists are running the debates. As long as the moderators can ask intelligent questions and tell people when their time is up, they’ll do. Journalists like to think they have unique abilities, but their profession doesn’t even require a high school diploma, let alone a graduate degree.
And then he could double down by saying he will hold the debate without her. The cable networks would have to cover him, because every other time Trump opens his mouth, he makes news.
You can read the rest of the piece on LifeZette.