Actually he does have the obligation to anticipate those questions. Just like when you go to court it is your obligation to anticipate what you would reasonably be asked and if you do not prepare yourself appropriately you will loose your case. He is the Attorney General of the United States. It is reasonable to expect that he has a clear understanding of exactly what he would be asked. If not, perhaps he needs a job that speaks better to his abilities to understand and anticipate legal issues.