Let's quote the relevant passage in which Craig pressed Crossan to be explicit about his views on God.
Crossan: …I would say what you’re trying to do is imagine the world without us. Now unfortunately, I can’t do that. If you were to ask me (which is just what you did) to abstract from faith how God would be if no human beings existed, that’s like asking me, “Would I be annoyed if I hadn’t been conceived?” I really don’t know how to answer that question.
Craig: Sure you do!
Crossan: Wait a minute! We know God only as God has revealed God to us; that’s all we could ever know in any religion.
Craig: During the Jurassic age, when there were no human beings, did God exist?
Crossan: Meaningless question.
Craig: But surely that’s not a meaningless question. It’s a factual question. Was there a being who was the Creator and Sustainer of the universe during the period of time when no human beings existed? It seems to me that in your view you’d have to say no.
Crossan: Well, I would probably prefer to say no because what you’re doing is trying to put yourself in the position of God and ask, “How is God apart from revelation? How is God apart from faith?” I don’t know if you can do that. You can do it, I suppose, but I don’t know if it really has any point.