No, I never got a response to my question.
I happen to come across this discussion. Until the past month, Jive Training and Support Resources was not monitoring questions in this space. There are more details on this in Ongoing Support Improvements: No Discussion Left Behind!
To answer your question:
Can you let me know how I can turn this feature off for a space or for our entire site?
There is not a current way to disable this feature. There is a setting in the Admin Console to increase the amount of Helpful Respsonse that will mark the question as assumed answered.
I would recommend voting up the idea Provide ability to disable "Assumed Answered" functionality to get this incorporated into a future release. Our Product Managers review the ideas and incorporate the highest voted ideas into the product.
Let us know if there are any further questions.