It's a question I have been asking myself.
I really dont understand what they think they can achieve. I saw the girl on Sky News this morning, oh deary deary me, she got ripped apart on the most basic of questions.
But back to the question. As you say if the answer was yes accept the deal then fine, but if it is no then how can it be anything but go with no deal. Of course it is clear that some see this as a back door to never leaving but others seem to think Tersa the Appeaser is the one doing the deal on the other side, they appear to have no comprehension that a negotiation is between two or more parties. And there is no way the EU will budge an inch, they have made it plain as the nose on your face that they intend to "punish" the UK for having the tenacity to leave their little club.
So "No" and leave with no deal and no payments seems good to me. Clean break and get on with it.