HPN has an hourly passenger cap that's part of the airline lease agreements. The terminal was also deliberately grossly underbuilt so that there's a natural restriction on the number of passengers that can fit in the secured area at any given time.

B6 would just have to find a time for the flight when the hourly passenger cap isn't already maxed out. A 1x weekly Saturday service should easily fit somewhere, if that's what B6 is envisioning. A daily service, perhaps not.