This will sound like a hot take, but consider that terrorists are for the most part, stupid idiots. All the information they need is in books and old patents and what-not, but they absolutely will not have as much success in synthesizing that into effective plans and well-made weapons without having a helpful and patient AI agent to guide them, as they will with that assist.
If the terrorists were very smart, they'd realize that their religion is stupid, that their leaders were mostly corrupt (or themselves stupid), and they'd also probably find something more productive to do with their time.
And obviously yes there are exceptions, since we can all think of infamous terrorist plots which succeeded due to clearly some sophisticated planning and hard work.