Hard to tell. I suspect the main thing for Newsnight was getting the interview regardless. She doesn't say this, but I'm guessing the negotiations they entered into had an element of reassuring him it wouldn't be a grilling. In fact given how the interview was set up it's astonishing he came out of it so badly.
Just one simple question I'd have liked:
are you willing to take a lie detector test? Realise they aren't that reliable, but I'd have liked her approach to have been a bit more investigative. Water under the bridge though, he came out of it appallingly anyway.