The problem I had, and why I added it, was that when the first connection is established, it blocks it because of this check. As you don't have an interactive session between the gateway and the host, it does not ask, just blocks it. I can remove it, but that would mean sshing into the gateway to ssh into the host first (so the keys are stored) and only after connecting using knife. Or adding another config option. Or maybe trying to make an interactive ssh session.