Taking a prisoner is pretty worthless. There is no meaningful intel to be gained from feral psycho's living in the woods. All you need to know is that they're there and will need to be dealt with; that's it.
Your using knowledge the characters don't have again. Which is why they needed to capture one for interrogation. They don't know if the wolves are crazy or not. In fact, the attack coming when most of the fighters are away from camp points to some planning and intent.
Talking to a prisoner and finding out that it's just some crazy cult psychos would have given them a leg up in how to handle them.
Now, they still have to guess as to what the wolves really want.