I really depends on how much he wants to control his network. If he wants to keep day to day control then there really are not that many places he could go.
Maintaing active control of his network would take to much communications for him to hide for long outside a predominatly Arab country. Also, it would have to be a country with poor border control, since many of the people he would want to see in person can not travel freely.
The obvious choice would be Somolia, there is no central government and he has many friends there. However, we already picked up on that possibility and the area must be heavily monitered.
India might work, simply because the country is so big. He should be able to find some out of the way area that is exclusivly Muslim.
Egypt would be nice in some ways, since it has better travel and communication access then other countries. But the government is already watching Muslim fanatics closely and Isreal has agents on the ground there. Actually, I think any country next to Isreal is probably out of the question for that very reason.
Iran is hard to call. It would have the advantage of shielding him from almost all outside scrutiny, but would make communication almost impossible. In any case it does not appear that the government of Iran like the version of Islam pushed by the Taliban, making such an alliance unlikely.
Iraq is a strong possiblity. Communications in and out would be very difficult, but he would be in little risk of being spotted. The government seems freindly to him, and is probably the only one that might activly protect him against the US. The strong down side is that we would have no qualms about a land invasion to get him out of Iraq, even if we didn't have 100% proof many would support a land assult there.
The only posibility that worries me is that he might head for Saudi Arabia. The government doesn't like him, but he has to have many contacts inside the country and probably has some in the government. The wealth of Saudia Arabia could be used to help cover many of his activities, people could be brought in on private jets without to much notice and so on.
The problem is Saudi Arabia is that if he is hiding there and we find out, what do we do? They are our ally after all, we can't bomb or attack them the way we might somebody else. At the same time the Saudi government is liable to have trouble finding and arresting him in a country where much of the population supports him.
Of course that all depends on him wanting to keep control of his network. If he is willing to hide and just make the occasional pronoucement against the US he could be just about anyplace. One of the Muslim Asian countries would probably be the best.
Jay