Even if he really had been a high-ranking member and was in on plans, arrangements, methods, etcetera, by now he would be so out of touch and out of date to be useless for any kind of information.
Actually, what they should have done with all of them, instead of torture, put them up in luxury-hotels, made sure that they had access to the internet and other communications and just listened in as well as talking to them in mutual respect. The latter worked for WWII interrogators far better than other methods. And if you give them opportunities to get in touch with their families and friends you will have a far better chance of getting information from their exchanges. A prison, however, stops all that and the harder you work to get information the less you get and the less the quality.