Those two are always going to balance each other, and are both experienced enough journos not to need reigning in or steering away from libel/contempt issues. Leaving them to it seems a perfectly valid way to host it.
That's true of the two people to whom you refer, but remember, it's principally the producer's job (most nights, me) to brief the guests on any sensitive legal areas (and sometimes to spare the feelings of guests whose papers might have printed stuff that Sky News as an Ofcom-regulated broadcaster doesn't feel comfortable running.)
That was really the point I was trying to make, that the presenter was able to take more of a back seat with those particular guests but on another night with different guests may need to steer the conversation to a greater degree or put a devil's advocate view etc. The implied criticism of a presenter for knowing when to keep quiet - I mean that in a completely complimentary way - is misplaced.
Write that down in your copybook now.