Given the first post, I think the question/concern is actually with a non-lit perpendicular runway which when used in calculating the circling area, would allow a greater distance from the lit runway when circling at night (when on downwind for example). Is this a problem? If you are maintaining the appropriate MDA, abiding by the appropriate Perf Cat speed limits and any 'no circling' restrictions there will be no problem as the obstacles and runways haven't moved just because there are no lights on the cross-runway!
The reference stating 'usable' runway for calculation is followed by a statement expressly stating that runways less than 1000m are not "considered usable" for Cat C,D & E. That should be a big hint as to what is being used to define 'usable' (ie. runway as appropriate to aircraft Perf Cat - no mention of runway lights).