I think Eliezer must have changed his mind after writing those words, because his TDT book was written for public consumption all along. (He gave two reasons for not publishing it sooner: he wanted to see if a university would offer him a PhD based on it, and he was using DT as a problem to test potential FAI researchers.) I guess his current lack of participation in our DT mailing list is probably due to some combination of being busy with his books and lack of significant new insights.