It seems like some are suggesting we should have forgotten about him. Ignoring the specific facts, he was an internationally wanted mass murder suspect. Generally speaking, we don't let murderers hide out because they don't want to stand trial. He has been wanted by the FBI for at least half my life.
No, he was not operationally the leader of any new plans, but he was still part of the group trying to hold the various factions together. Even recently, he was releasing recordings of threats. While it might increase the threat to us for a while, it does show that we can find well hidden terrorist leaders, this would not be a good time to be #2 in their leadership.