Oh this is absolutely another problem for supersonic time savings.

Supersonic flight over the continents is problematic, but not everyone lives on a coast. So many customers will have to take slow planes to aggregation hubs, which can easily add hours to an itinerary. Edit: And the aggregation hubs may not all serve the same destinations. Could easily see SF residents having to fly commercial to NYC to catch a Boom to London, even though there might be a Boom that flies SF-Tokyo.

Once you add up the fixed time costs of getting to the airport, security, flying to a supersonic hub, the percentage of time that can potentially be shaved off the itinerary dwindles.

The point was that you get to bypass a lot of the usual airport routine with private and also have greater flexibility when you fly. (Though flight plans still need to be filed and airport runways can still be congested.)

And, yes, a private supersonic would be even faster but then it becomes even more of a question about the size of the market.