I assumed you didn't mean literally anything. But I'm also assuming you know very little about debate tactics, is that correct? If so, the sentence I quoted seems to imply you seem to think you should be able to handle quite a wide range of things on the fly.

Craig is selective about who he debates, but mostly he seems to be optimizing for how big of names his opponents are. As much as I respect your work, Eliezer, you simply aren't as big of a name as Sam Harris or Christopher Hitchens (who've debate Craig) or Jerry Coyne (who recently declined a debate invitation from Craig).

I can suspect him of cowardice when he refuses to debate Jeffrey Jay Lowder (who like Craig and unlike most of Craig's opponents, has a background in college debate), but unless you've got some amazing debate performances under your belt that I don't know about, I don't think fear of losing is the reason he refused to debate you.