That's fair--400 miles is on the shorter end of the spectrum.

Still, "low cost" is relative to a chartered private jet--which, emphatically, is not a service that people purchase because it's the most economical option--rather than a commercial airliner (although, if true, the SFC per passenger of the Celera would be in the same ballpark as modern commercial airliners, which is very impressive). The average domestic flight is under 1000 statute miles (https://www.bts.gov/content/average-length-haul-domestic-fre...), so this plane needs to offer compelling efficiency gains at ~500-1500 mile ranges in order to compete with existing services, unless they're strictly planning to fill the niche of one-leg, long-range flights that existing private jets don't have the legs for.

No, they intend to compete with like commercial travel, maybe business class at first, in price per seat per trip to charter an aircraft like this.

$300/hour charter price with 6 seats for a 5 hour trip (2000 miles) is about $250 per seat each way. This is pretty competitive.

$328/hr is the advertised operating cost of the aircraft (fuel and maintenance), not anything close to what a charter would actually charge. Commercial airline operating costs, including crew salary and overhead, are roughly an order of magnitude more (~$3000/hour is a rough, somewhat conservative, number for something like a B737, including fuel, crew, maintenance, and aircraft depreciation/rental costs). The airline is paying under $20 per passenger-hour for all expenses, while a charter service operating with volunteer pilots, free airplanes, and no other costs would break even at ~$55 per passenger-hour (assuming the $328/hr estimate is accurate, which is still very much an open question for an aircraft that's still undergoing initial flight testing and may never be produced in significant volume). Even the best-case scenario doesn't strike me as particularly competitive.