"Many in that class of traveler would arrive by private aircraft."

You bet and the runway clearly has those 1% in mind. But those types also have friends, family, business associates who come and go before, during, and after their visit on commercial. Some of the group may come in with the principle on a private jet but in most cases some of the group will return early, come late, or go to a different direction on the globe by commercial. Pick your favorite very rich person with jet access. They are not traveling with everyone in the group on the way in and out for a list of reasons way to long to type. Others will not go anywhere and in some cases are not allowed by their employee contract to go anywhere where a FAA 135 air ambulance cannot come to pick them up. Again the modern reliable runway is table stakes for future BVI property values and local employment.